Effects of Androgen Deprivation Therapy on Prostate Cancer Outcomes According to Competing Event Risk: Secondary Analysis of a Phase 3 Randomised Trial

BACKGROUND

Previous studies indicate that the benefit of short-term androgen deprivation therapy (ADT) with radiotherapy (RT) for prostate cancer depends on competing risks.

OBJECTIVE

To determine whether a quantitative method to stratify patients by risk for competing events (omega score) could identify subgroups that selectively benefit from ADT.

DESIGN, SETTING, AND PARTICIPANTS

An ancillary analysis of NRG/RTOG 9408 phase 3 trial (NCT00002597) involving 1945 prostate cancer patients was conducted.

INTERVENTION

Short-term ADT.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

We applied generalised competing event regression models incorporating age, performance status, comorbidity, T category, Gleason score (GS), and prostate-specific antigen (PSA), to stratify patients according to relative hazards for primary cancer-related events (distant metastasis or prostate cancer death) versus competing noncancer mortality. We tested interactions between ADT and subgroups defined by standard risk criteria versus relative risk (RR) using the omega score.

RESULTS AND LIMITATIONS

T2b, higher GS, and higher PSA were associated with an increased RR for cancer-related versus competing mortality events (a higher omega score); increased age and comorbidity were associated with a decreased omega score. Of 996 patients with low-risk/favourable intermediate-risk (FIR) disease, 286 (28.7%) had a high omega score (≥0.314). Of 768 patients with unfavourable intermediate-risk disease, 175 (22.8%) had a low omega score. The overall discordance in risk classification was 26.1%. Both standard criteria and omega score identified significant interactions for the effect of ADT on cancer-related events and late mortality in low- versus high-risk subgroups. Within the low-risk/FIR subgroup, a higher omega score identified patients in whom ADT significantly reduced cancer events and improved event-free survival. Limitations are the need for external/prospective validation and lower RT doses than contemporary standards.

CONCLUSIONS

Stratification based on competing event risk is useful for identifying prostate cancer patients who selectively benefit from ADT.

PATIENT SUMMARY

We analysed the effectiveness of androgen deprivation therapy (ADT) for localised prostate cancer among patients, defined by the relative risk (RR) for cancer versus noncancer events. Among patients with traditional low-risk/favourable intermediate-risk disease, those with a higher RR benefitted from short-term ADT.

Safety Analyses of the Phase 3 VISION Trial of [177Lu]Lu-PSMA-617 in Patients with Metastatic Castration-resistant Prostate Cancer

BACKGROUND AND OBJECTIVE

[177Lu]Lu-PSMA-617 (177Lu-PSMA-617) plus the standard of care (SoC) significantly improved overall survival and radiographic progression-free survival versus SoC alone in patients with prostate-specific membrane antigen (PSMA)-positive metastatic castration-resistant prostate cancer in the VISION trial. We evaluated the safety of additional cycles of 177Lu-PSMA-617 and the impact of longer observation time for patients receiving 177Lu-PSMA-617 plus SoC.

METHODS

VISION was an international, open-label study. Patients were randomised 2:1 to receive 177Lu-PSMA-617 plus SoC or SoC alone. The incidence of treatment-emergent adverse events (TEAEs) was assessed in prespecified subgroups of patients who received ≤4 cycles versus 5-6 cycles of treatment and during each cycle of treatment. The TEAE incidence was also adjusted for treatment exposure to calculate the incidence per 100 patient-treatment years of observation. This analysis was performed for the first occurrence of TEAEs.

KEY FINDINGS AND LIMITATIONS

The any-grade TEAE incidence was similar in cycles 1-4 and cycles 5-6. TEAE frequency was similar across all cycles of 177Lu-PSMA-617 treatment. No additional safety concerns were reported for patients who received >4 cycles. The exposure-adjusted safety analysis revealed that the overall TEAE incidence was similar between arms, but distinct trends for different TEAE types were noted and the incidence of events associated with 177Lu-PSMA-617 remained higher in the 177Lu-PSMA-617 arm.

CONCLUSIONS AND CLINICAL IMPLICATIONS

Longer exposure to 177Lu-PSMA-617 plus SoC was not associated with a higher toxicity risk, and the extended time for safety observation could account for the higher TEAE incidence in comparison to SoC alone. The findings support a favourable benefit-risk profile for 6 cycles of 177Lu-PSMA-617 in this setting and the use of up to 6 cycles of 177Lu-PSMA-617 in patients who are clinically benefiting from and tolerating this therapy.

PATIENT SUMMARY

For patients with metastatic prostate cancer no longer responding to hormone therapy, an increase in the number of cycles of treatment with a radioactive compound called 177Lu-PSMA-617 from four to six had no additional adverse side effects.

Noninferiority of Hypofractionated vs Conventional Postprostatectomy Radiotherapy for Genitourinary and Gastrointestinal Symptoms: The NRG-GU003 Phase 3 Randomized Clinical Trial

Importance

No prior trial has compared hypofractionated postprostatectomy radiotherapy (HYPORT) to conventionally fractionated postprostatectomy (COPORT) in patients primarily treated with prostatectomy.

Objective

To determine if HYPORT is noninferior to COPORT for patient-reported genitourinary (GU) and gastrointestinal (GI) symptoms at 2 years.

Design, Setting, and Participants

In this phase 3 randomized clinical trial, patients with a detectable prostate-specific antigen (PSA; ≥0.1 ng/mL) postprostatectomy with pT2/3pNX/0 disease or an undetectable PSA (<0.1 ng/mL) with either pT3 disease or pT2 disease with a positive surgical margin were recruited from 93 academic, community-based, and tertiary medical sites in the US and Canada. Between June 2017 and July 2018, a total of 296 patients were randomized. Data were analyzed in December 2020, with additional analyses occurring after as needed.

Intervention

Patients were randomized to receive 62.5 Gy in 25 fractions (HYPORT) or 66.6 Gy in 37 fractions (COPORT).

Main Outcomes and Measures

The coprimary end points were the 2-year change in score from baseline for the bowel and urinary domains of the Expanded Prostate Cancer Composite Index questionnaire. Secondary objectives were to compare between arms freedom from biochemical failure, time to progression, local failure, regional failure, salvage therapy, distant metastasis, prostate cancer-specific survival, overall survival, and adverse events.

Results

Of the 296 patients randomized (median [range] age, 65 [44-81] years; 100% male), 144 received HYPORT and 152 received COPORT. At the end of RT, the mean GU change scores among those in the HYPORT and COPORT arms were neither clinically significant nor different in statistical significance and remained so at 6 and 12 months. The mean (SD) GI change scores for HYPORT and COPORT were both clinically significant and different in statistical significance at the end of RT (-15.52 [18.43] and -7.06 [12.78], respectively; P < .001). However, the clinically and statistically significant differences in HYPORT and COPORT mean GI change scores were resolved at 6 and 12 months. The 24-month differences in mean GU and GI change scores for HYPORT were noninferior to COPORT using noninferiority margins of -5 and -6, respectively, rejecting the null hypothesis of inferiority (mean [SD] GU score: HYPORT, -5.01 [15.10] and COPORT, -4.07 [14.67]; P = .005; mean [SD] GI score: HYPORT, -4.17 [10.97] and COPORT, -1.41 [8.32]; P = .02). With a median follow-up for censored patients of 2.1 years, there was no difference between HYPORT vs COPORT for biochemical failure, defined as a PSA of 0.4 ng/mL or higher and rising (2-year rate, 12% vs 8%; P = .28).

Conclusions and Relevance

In this randomized clinical trial, HYPORT was associated with greater patient-reported GI toxic effects compared with COPORT at the completion of RT, but both groups recovered to baseline levels within 6 months. At 2 years, HYPORT was noninferior to COPORT in terms of patient-reported GU or GI toxic effects. HYPORT is a new acceptable practice standard for patients receiving postprostatectomy radiotherapy.

Trial Registration

ClinicalTrials.gov Identifier: NCT03274687.

Handling Patient Emergencies During Radiopharmaceutical Therapy

PURPOSE

Radiopharmaceutical therapy (RPT) is a rapidly growing treatment modality. Though uncommon, patients may experience complications during their RPT treatment, which may trigger a rapid response from the hospital team. However, members of this team are typically not familiar with precautions for radiation safety. During these events, it is important to prioritize the patient's health over all else. There are some practices that can help minimize the risk of radiation contamination spread and exposure to staff while tending to the patient.

METHODS AND MATERIALS

We formed a team to develop a standard protocol for handling patient emergencies during RPT treatment. This team consisted of an authorized user, radiation safety officer, medical physicist, nurse, RPT administration staff, and a quality/safety coordinator. The focus for developing this standardized protocol for RPT patient emergencies was 3-fold: (1) stabilize the patient; (2) reduce radiation exposure to staff; and (3) limit the spread of radiation contamination.

RESULTS

We modified our hospital's existing rapid response protocol to account for the additional staff and tasks needed to accomplish all 3 of these goals. Each team member was assigned specific responsibilities, which include serving as a gatekeeper to restrict traffic, managing the crash cart, performing chest compressions, timing chest compressions, documenting the situation, and monitoring/managing radiation safety in the area. We developed a small, easy-to-read card for rapid response staff to read while they are en route to the area so they can be aware of and prepare for the unique circumstances that RPT treatments present.

CONCLUSIONS

Though rapid response events with RPT patients are uncommon, it is important to have a standardized protocol for how to handle these situations beforehand rather than improvise in the moment. We have provided an example of how our team adapted our hospital's current rapid response protocol to accommodate RPT patients.

Cardiovascular Mortality and Duration of Androgen Deprivation in Locally Advanced Prostate Cancer: Long-term Update of NRG/RTOG 9202

BACKGROUND

Androgen deprivation therapy (ADT) has been associated with coronary heart disease and myocardial infarction (MI) in prostate cancer patients, but controversy persists regarding its effects on cardiovascular mortality (CVM).

OBJECTIVE

We assessed the long-term relationship between ADT and CVM in a prostate cancer randomized trial (NRG Oncology/Radiation Therapy Oncology Group 9202).

DESIGN, SETTING, AND PARTICIPANTS

From 1992 to 1995, 1554 men with locally advanced prostate cancer (T2c-T4, prostate-specific antigen <150 ng/ml) received radiotherapy with 4 mo (short-term [STADT]) versus 28 mo (longer-term [LTADT]) of ADT.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Using the Fine-Gray and Cox regression models, the relationship between ADT and mortality was evaluated.

RESULTS AND LIMITATIONS

With a median follow-up of 19.6 yr, LTADT was associated with improved overall survival (OS) versus STADT (adjusted hazard ratio [HR] 0.88; p = 0.03) and prostate cancer survival (subdistribution HR [sHR] 0.70, p = 0.003). Comparing LTADT with STADT, prostate cancer mortality improved by 6.0% (15.6% [95% confidence interval 13.0-18.3%] vs 21.6% [18.6-24.7%]) at 15 yr, while CVM increased by 2.2% (14.9% [12.4-17.6%] vs 12.7% [10.4-15.3%]). In multivariable analyses, LTADT was not associated with increased CVM versus STADT (sHR 1.22 [0.93-1.59]; p = 0.15). An association between LTADT and MI death was detected (sHR 1.58 [1.00-2.50]; p = 0.05), particularly in patients with prevalent cardiovascular disease (CVD; sHR 2.54 [1.16-5.58]; p = 0.02).

CONCLUSIONS

With 19.6 yr of follow-up, LTADT was not significantly associated with increased CVM in men with locally advanced prostate cancer. Patients may have increased MI mortality with LTADT, particularly those with baseline CVD. Overall, there remained a prostate cancer mortality benefit and no OS detriment with LTADT.

PATIENT SUMMARY

In a long-term analysis of a large randomized prostate cancer trial, radiation with 28 mo of hormone therapy did not increase the risk of cardiovascular death significantly versus 4 mo of hormone therapy. Future studies are needed for patients with pre-existing heart disease, who may have an increased risk of myocardial infarction death with longer hormone use.

External Validation of a Digital Pathology-based Multimodal Artificial Intelligence Architecture in the NRG/RTOG 9902 Phase 3 Trial

BACKGROUND

Accurate risk stratification is critical to guide management decisions in localized prostate cancer (PCa). Previously, we had developed and validated a multimodal artificial intelligence (MMAI) model generated from digital histopathology and clinical features. Here, we externally validate this model on men with high-risk or locally advanced PCa treated and followed as part of a phase 3 randomized control trial.

OBJECTIVE

To externally validate the MMAI model on men with high-risk or locally advanced PCa treated and followed as part of a phase 3 randomized control trial.

DESIGN, SETTING, AND PARTICIPANTS

Our validation cohort included 318 localized high-risk PCa patients from NRG/RTOG 9902 with available histopathology (337 [85%] of the 397 patients enrolled into the trial had available slides, of which 19 [5.6%] failed due to poor image quality).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Two previously locked prognostic MMAI models were validated for their intended endpoint: distant metastasis (DM) and PCa-specific mortality (PCSM). Individual clinical factors and the number of National Comprehensive Cancer Network (NCCN) high-risk features served as comparators. Subdistribution hazard ratio (sHR) was reported per standard deviation increase of the score with corresponding 95% confidence interval (CI) using Fine-Gray or Cox proportional hazards models.

RESULTS AND LIMITATIONS

The DM and PCSM MMAI algorithms were significantly and independently associated with the risk of DM (sHR [95% CI] = 2.33 [1.60-3.38], p < 0.001) and PCSM, respectively (sHR [95% CI] = 3.54 [2.38-5.28], p < 0.001) when compared against other prognostic clinical factors and NCCN high-risk features. The lower 75% of patients by DM MMAI had estimated 5- and 10-yr DM rates of 4% and 7%, and the highest quartile had average 5- and 10-yr DM rates of 19% and 32%, respectively (p < 0.001). Similar results were observed for the PCSM MMAI algorithm.

CONCLUSIONS

We externally validated the prognostic ability of MMAI models previously developed among men with localized high-risk disease. MMAI prognostic models further risk stratify beyond the clinical and pathological variables for DM and PCSM in a population of men already at a high risk for disease progression. This study provides evidence for consistent validation of our deep learning MMAI models to improve prognostication and enable more informed decision-making for patient care.

PATIENT SUMMARY

This paper presents a novel approach using images from pathology slides along with clinical variables to validate artificial intelligence (computer-generated) prognostic models. When implemented, clinicians can offer a more personalized and tailored prognostic discussion for men with localized prostate cancer.

Does Chemo-Radiotherapy Improve Survival Outcomes vs. Radiotherapy Alone for High-Grade cT1 Urothelial Carcinoma of the Bladder?

BACKGROUND

Non-muscle invasive bladder cancer (non-MIBC) that is high-grade and confined to the lamina propria (HGT1) often has an aggressive clinical course. Currently, there is limited data on the comparative effectiveness of RT vs. CRT for HGT1 non-MIBC. We hypothesized that CRT would be associated with improved overall survival (OS) vs. RT in HGT1 bladder cancer.

METHODS

Patients diagnosed with HGT1 non-MIBC, and treated with transurethral resection of bladder tumor followed by either treatment with RT alone or CRT, were identified in the National Cancer Database. Inverse probability of treatment weighting (IPTW) was employed and weight-adjusted multivariable analysis (MVA) using Cox regression modeling was used to compare overall survival (OS) hazard ratios. OS was the primary endpoint, and was estimated using the Kaplan-Meier method and log-rank tests.

RESULTS

A total of 259 patients with HGT1 UC were treated with: (i) RT alone (n = 123) or (ii) CRT (n = 136). Propensity-weighted MVA showed that combined modality treatment with CRT was associated with improved OS relative to radiation alone (Hazard Ratio [HR]: 0.62, 95% Confidence Interval (95% CI): 0.44-0.88, P = .007). Four-year OS for the CRT vs. RT alone was 36% and 19%, respectively (log-rank P <.008).

CONCLUSION

For patients with HGT1 bladder cancer, concurrent CRT was associated with improved OS compared with radiation alone in a retrospective cohort. These results are hypothesis-generating. The NRG is currently developing a phase II randomized clinical trial comparing CRT to other novel, bladder preservation strategies.

Biochemical Recurrence Surrogacy for Clinical Outcomes After Radiotherapy for Adenocarcinoma of the Prostate

PURPOSE

The surrogacy of biochemical recurrence (BCR) for overall survival (OS) in localized prostate cancer remains controversial. Herein, we evaluate the surrogacy of BCR using different surrogacy analytic methods.

MATERIALS AND METHODS

Individual patient data from 11 trials evaluating radiotherapy dose escalation, androgen deprivation therapy (ADT) use, and ADT prolongation were obtained. Surrogate candidacy was assessed using the Prentice criteria (including landmark analyses) and the two-stage meta-analytic approach (estimating Kendall's tau and the R2). Biochemical recurrence-free survival (BCRFS, time from random assignment to BCR or any death) and time to BCR (TTBCR, time from random assignment to BCR or cancer-specific deaths censoring for noncancer-related deaths) were assessed.

RESULTS

Overall, 10,741 patients were included. Dose escalation, addition of short-term ADT, and prolongation of ADT duration significantly improved BCR (hazard ratio [HR], 0.71 [95% CI, 0.63 to 0.79]; HR, 0.53 [95% CI, 0.48 to 0.59]; and HR, 0.54 [95% CI, 0.48 to 0.61], respectively). Adding short-term ADT (HR, 0.91 [95% CI, 0.84 to 0.99]) and prolonging ADT (HR, 0.86 [95% CI, 0.78 to 0.94]) significantly improved OS, whereas dose escalation did not (HR, 0.98 [95% CI, 0.87 to 1.11]). BCR at 48 months was associated with inferior OS in all three groups (HR, 2.46 [95% CI, 2.08 to 2.92]; HR, 1.51 [95% CI, 1.35 to 1.70]; and HR, 2.31 [95% CI, 2.04 to 2.61], respectively). However, after adjusting for BCR at 48 months, there was no significant treatment effect on OS (HR, 1.10 [95% CI, 0.96 to 1.27]; HR, 0.96 [95% CI, 0.87 to 1.06] and 1.00 [95% CI, 0.90 to 1.12], respectively). The patient-level correlation (Kendall's tau) for BCRFS and OS ranged between 0.59 and 0.69, and that for TTBCR and OS ranged between 0.23 and 0.41. The R2 values for trial-level correlation of the treatment effect on BCRFS and TTBCR with that on OS were 0.563 and 0.160, respectively.

CONCLUSION

BCRFS and TTBCR are prognostic but failed to satisfy all surrogacy criteria. Strength of correlation was greater when noncancer-related deaths were considered events.

A pooled long-term follow-up after radiotherapy for prostate cancer with and without a rectal hydrogel spacer: impact of hydrogel on decline in sexual quality of life

Purpose

The purpose of this study was to analyze the impact of prostate rectal spacers on sexual quality of life (QOL) following external beam radiation therapy (RT).

Methods and materials

Patient- reported QOL was evaluated using the Expanded Prostate Cancer Index Composite (EPIC). Patients were pooled from two sources: a randomized controlled trial and a non-randomized cohort of patients from a single institution. Both cohorts used the same spacing product and QOL instrument. Analysis was limited to those with good baseline pre-treatment sexual QOL (EPIC >/= 60). Differences in QOL summary score and individual items were assessed compared with baseline and between treatment arms.

Results

A total of 128 men had good baseline sexual function and were evaluated (64% with spacer and 36% without) with QOL data available for median 33 months (range: 2.5-69.4 months). Men without spacer were more likely to have declines in sexual function (p < 0.0001), bother (p = 0.0002), and sexual summary score (p < 0.0001). A minimally important difference of 10 points (1xMID) and 20 point (2xMID) was more likely without rectal spacer [10 points: odds ratio 3.53, (95% confidence interval 1.11-11.2), p = 0.032; 20 points: odds ratio 3.29, (95% confidence interval 1.16-9.33), p = 0.025]. Seven of 13 QOL items were statistically superior with hydrogel (six of nine functional and one of four bother), while no items were statistically superior for control. At baseline, more men treated with hydrogel had erections sufficient for intercourse; however, when analyzed only by the men with best baseline erectile potential and excluding those with worse function, the benefit of rectal spacing was maintained with a higher likelihood of preservation of erections sufficient for intercourse in those treated with hydrogel.

Conclusion

In this pooled analysis of QOL after prostate RT, the utilization of a hydrogel spacer was associated with better sexual QOL, less men with measurable declines in sexual QOL, and higher rates of adequate erectile function.

Bridging the Gap of Radiotherapy Treatment Planning Quality between High-Income, and Low- and Middle-Income Countries Using Knowledge-Based Planning

PURPOSE/OBJECTIVE(S)

Radiotherapy departments in low- and middle-income countries (LMICs) like Guatemala have recently introduced intensity-modulated radiotherapy (IMRT). IMRT has become the standard of care in high-income countries (HIC) due to reduced toxicity and improved outcomes in some cancers. The purpose of this work is to show the feasibility of adapting knowledge-based (KB) models established in a HIC to a LMIC lacking experience in IMRT to improve plan quality and planning efficiency.

MATERIALS/METHODS

A Halcyon Linac was installed at our clinic in Guatemala in 2019 and has been used to treat approximately 90 patients daily with IMRT. A model developed on a cohort of head and neck cancer patients at a US academic radiotherapy center were applied at our center to create 20head and neck VMAT plans with different prescriptions, including simultaneous-integrated and sequential boosts.

RESULTS

The plans created using the KB models achieved similar coverage of the planning target volume for each plan KB plans showed better 1) Parotid sparing with a mean dose reduction between 5%-25% and spinal cord maximum dose reduction between 3%-15%. The time efficiency to create VMAT plans using KB model versus manual planning improved four-fold, on average one hour versus more than 4 hours, respectively.

CONCLUSION

Despite different prescriptions, guidelines and demographics of cancer patients between two institutions in a HIC and LMIC, this work demonstrates that KB planning can be used to generate better and more consistent VMAT plans versus manually created plans. In addition, KB planning has the potential to greatly increase planning efficiency higher efficiency and help address the shortage of medical physicists and dosimetrists in LMICs.

Detection Rate of 18F-rhPSMA-7.3 PET in Patients with Suspected Prostate Cancer Recurrence at PSA Levels <1 ng/mL: Data from the Phase 3 SPOTLIGHT Study

PURPOSE/OBJECTIVE(S)

Novel molecular imaging agents yield potential for localization of disease in patients with biochemical recurrence of prostate cancer when PSA levels are still low, and may facilitate early intervention with selective therapy to optimize outcomes. Radiohybrid (rh) positron emission tomography (PET) radiopharmaceutical, 18F-rhPSMA-7.3, is a novel high affinity prostate-specific membrane antigen (PSMA)-targeting ligand with potential for low bladder activity. The SPOTLIGHT study (NCT04186845) evaluated the diagnostic performance of 18F-rhPSMA-7.3 in men with suspected prostate cancer recurrence. Here, we report findings from a post-hoc analysis of SPOTLIGHT data, which determined the 18F-rhPSMA-7.3 detection rates (DR) at low-very low PSA levels.

MATERIALS/METHODS

Patients enrolled in SPOTLIGHT underwent PET 50-70 min after IV administration of 296 MBq 18F-rhPSMA-7.3. Scans were evaluated by 3 blinded central readers, with the majority read representing agreement between ≥2 independent readers. For the present analysis, all patients with an evaluable 18F-rhPSMA-7.3 PET and who had a baseline PSA <1 ng/mL were selected. Overall (patient-level) and regional DR by majority read were determined, stratifying DR according to the patients' baseline PSA level (<0.2, ≥0.2 - <0.3, ≥0.3 - <0.5, and ≥0.5 - <1 ng/mL).

RESULTS

In total, 389 patients (median [range] PSA, 1.10 [0.03-135] ng/mL, 84 with intact prostate) had an evaluable 18F-rhPSMA-7.3 scan. The overall DR was 83% (322/389) by majority read. Of the 389 patients with an evaluable 18F-rhPSMA-7.3 scan, 188 had a baseline PSA <1 ng/mL and were eligible for the present analysis. Despite low patient numbers in some PSA categories, moderate to high DR were observed, with the patient-level DR shown to increase with increasing baseline PSA (see table). Overall, 68% (128/188) of patients with a PSA <1 ng/mL and 64% (77/121) of patients with a PSA <0.5 ng/mL had a positive 18F-rhPSMA-7.3 scan by majority read. Regional DR were broadly consistent across all PSA categories. Of note, extrapelvic lesions were observed in 21% (25/121) of patients with a PSA <0.5 ng/mL and 27% (51/188) of all patients with a PSA <1 ng/mL.

CONCLUSION

Among this cohort of patients with low-very low PSA levels, more than two-thirds were found to have positive 18F-rhPSMA-7.3 scans. Of clinical significance, over a quarter of patients had extrapelvic findings. 18F-rhPSMA-7.3 PET may be a useful tool for treatment planning in patients with early biochemical recurrence of prostate cancer where curative salvage therapy is of prime consideration.

Impact of Testosterone Recovery on Clinical Outcomes of Patients Treated with Salvage Radiotherapy and Androgen Suppression: A Secondary Analysis of the NRG/RTOG 0534 Sport Phase 3 Trial

PURPOSE/OBJECTIVE(S)

Testosterone (T) kinetics and its relationship with clinical outcomes has not been studied in trials using salvage radiotherapy and androgen deprivation therapy (ADT). We performed a secondary analysis of the NRG Oncology/RTOG 0534 SPPORT trial, which compared prostate bed radiotherapy (PBRT) (arm 1), PBRT + short-term androgen deprivation therapy (ADT) (arm 2), or PBRT + pelvic lymph node radiotherapy (PLNRT) + short-term ADT (arm 3). We assessed longitudinal serum T levels and the impact of testosterone recovery (TR) on clinical outcomes.

MATERIALS/METHODS

ADT was given for 4-6 months in arms 2 and 3, starting 2 months prior to radiotherapy. The trial excluded patients with baseline T < 40% of the lower limit of normal. TR was defined in 3 ways: 1) return to non-castrate level (>50 ng/dL), 2) return to normal level (>300 ng/dL), and 3) return to baseline level. Time to TR was estimated using cumulative incidence and death without an event considered a competing risk. Unadjusted and adjusted hazard ratios and 95% confidence intervals (CIs) were calculated using Cox proportional hazards model. Freedom from progression (FFP) was defined as biochemical failure according to the Phoenix definition (PSA ≥2 ng/mL over the nadir PSA), clinical failure (local, regional, or distant), or death from any cause.

RESULTS

A total of 1699 patients with T at baseline and at least 1 follow-up assessment were included. The median age was 64 years (IQR 59 - 69), 12.8% were black, 14.9% had diabetes, and 54.1% were former or current smokers. Median baseline T in arms 1, 2 and 3 was 320 ng/dL (IQR 239 - 424), 319 ng/dL (IQR 237 - 438) and 330 ng/dL (IQR 252 - 446), respectively. At 6 months, median T in arms 1, 2 and 3 was 290 ng/dL (IQR 210 - 390), 190.4 ng/dL (IQR 66 - 296) and 191 ng/dL (IQR 40.5 - 313). At 2 years, in arms 2 and 3, TR to non-castrate, normal and baseline levels were 95%, 55% and 23%, respectively. At 5 years, in arms 2 and 3, TR to non-castrate, normal and baseline levels were 98%, 73% and 42%, respectively. FFP was superior in arms 2 and 3 vs. arm 1 in patients with TR by all three definitions. In patients with recovered T to normal levels by 2 years (n = 904), the 5-year FFP rates were 71.8% (95% CI 66.9-76.6) in arm 1, 77.2% (72.1-82.2) in arm 2, and 86.3% (82.3-90.3) in arm 3 (arm 2 vs arm 1: HR 0.74, 95% CI 0.56-0.98, p = 0.034; arm 3 vs arm 1: HR 0.54, 95% CI 0.40-0.72, p<.0001).

CONCLUSION

This work represents the largest study of T kinetics in patients treated with salvage radiation and ADT. Approximately half of patients did not normalize their T levels by 2 years. Our data validate an incremental and meaningful FFP benefit of adding short-term ADT and PLNRT to PBRT independent of T recovery.

Long-Term Outcomes of NRG/RTOG 0126, a Randomized Trial of High Dose (79.2 Gy) vs. Standard Dose (70.2 Gy) Radiation Therapy (RT) for Men with Localized Prostate Cancer

PURPOSE/OBJECTIVE(S)

NRG/RTOG 0126, a phase III trial for men with localized prostate cancer testing whether dose escalation to 79.2 Gy with 3DCRT/IMRT improved overall survival (OS). Long-term results of this trial are presented.

MATERIALS/METHODS

Patients with clinical stage T1b-T2b and either Gleason Score (GS) 2-6 and 10 ≤ PSA < 20 or GS 7 and PSA < 15 were eligible and randomized to receive 79.2 Gy or 70.2 Gy. No previous or concurrent androgen withdrawal therapy was administered. Treatment was delivered with 3DCRT/IMRT to a dose of 79.2 Gy in 44 fractions or 70.2 Gy in 39 fractions to the PTV encompassing the prostate and seminal vesicles. Image guidance was not required. ASTRO and Phoenix definitions were used for biochemical failure (ABF and PBF, respectively). OS was estimated by the Kaplan-Meier method and arms compared with the log-rank test. ABF, PBF, local progression (LP), distant metastases (DM) and time to late GI/GU toxicities were estimated by the cumulative incidence method and arms compared with Gray's test.

RESULTS

One thousand five hundred thirty-two men were randomized, 763 to 79.2 Gy and 769 to 70.2 Gy. 1499 were eligible, 748 and 751 in the 79.2 Gy and 70.2 Gy arms respectively. Median age was 71, 70% had PSA < 10 ng/ml, 84% with GS 7, 57% had T1 disease, and 66% treated with 3D-CRT. Outcomes are shown in the TABLE: . With a median follow up of 12 years, there was no significant difference in OS. There was a statistically significant decrease in the cumulative incidence of ABF, PBF, DM, LP, and salvage therapies in the 79.2 Gy arm. There were significantly higher rates of grade 2+ GI and GU toxicity in the 79.2 Gy arm. There were no statistically significant differences in the rates of grade 3+ GU or GI toxicity between either arm.

CONCLUSION

Long term follow up confirms no improvement in OS with dose escalation in this study population. However, there are significant improvements in ABF, PBF, DM, LP, and need for salvage therapy. Despite the use of more salvage therapy in the low dose arm, dose escalated RT resulted in lower rates of DM, a clinically relevant endpoint. Patients receiving dose escalation do experience a higher rate of grade 2+ GU and GI toxicity but no worse grade 3+ toxicities.

Prostate Advanced Radiation Technologies Investigating Quality of Life (PARTIQoL): A Phase III Randomized Clinical Trial of Proton Therapy vs. IMRT for Low or Intermediate Risk Prostate Cancer

PURPOSE/OBJECTIVE(S)

Prostate cancer is the most common non-cutaneous cancer diagnosed among men in the United States, and the majority of patients are diagnosed with localized disease. Men with localized prostate cancer have several treatment options including external beam radiotherapy with either photons or protons. Proton beam therapy (PBT) has certain dosimetric advantages and the potential to reduce treatment-associated morbidity and improve oncologic outcomes, but current PBT is significantly more costly than intensity-modulated radiotherapy (IMRT). The PARTIQoL trial (NCT01617161) is the first multicenter phase 3 randomized trial comparing protons to photons in the treatment of localized prostate cancer.

MATERIALS/METHODS

Patients with low or intermediate risk prostate cancer (Stage T1c-T2c, PSA < 20, Gleason score ≤ 7) are randomized to receive either PBT or IMRT, with targeted recruitment efforts for minority populations. A companion registry study has concurrently enrolled patients who declined randomization or whose insurance denied coverage for PBT. Patients are stratified by clinical site, age, use of rectal spacer, and fractionation schedule (conventional fractionation: 79.2 Gy in 44 fractions vs moderate hypofractionation: 70.0 Gy in 28 fractions). Participants are followed longitudinally to assess patient-reported outcomes (PROs) of bowel, urinary, and erectile function for 60 months after completion of radiotherapy (with an option for additional follow up through 10 years). Participants may also participate in correlative studies, including serial CT imaging during treatment and analyses of biopsy tissue, blood and urine specimens. The primary objective is to compare PROs of bowel function using the EPIC score at 24 months following completion of radiation. Secondary objectives are to assess treatment-related differences in urinary and erectile functions, adverse events, efficacy endpoints (biochemical control, metastasis-free survival, disease-specific survival, and overall survival), health state utilities, perceptions of care, late effects, cost-effectiveness, association between radiotherapy dose distribution and PROs, and to identify biomarkers of radiation response and toxicity.

RESULTS

The randomized trial has completed accrual, with 450 patients enrolled at 27 sites between June 2012 and November 2021. 20.3% of patients enrolled are non-white. Accrual on the companion registry is active, with 354 patients enrolled as of February 2023.

CONCLUSION

Follow-up for the primary endpoint on the randomized trial will be reached in 2024. The PARTIQoL randomized clinical trial will rigorously assess the clinical benefits of PBT relative to IMRT and results will inform decision making by patients, providers, policymakers, and payers.

Standardizing LT Chest Wall Radiotherapy Treatment Planning in a Low- or Middle- Income Country Radiotherapy Clinic Using Knowledge Based Planning

PURPOSE/OBJECTIVE(S)

Radiotherapy departments in low- or middle-income countries (LMICs) tend to lag behind introducing emerging technologies like intensity-modulated radiotherapy (IMRT). IMRT has become the standard of care in high-income countries (HIC) due to reduced toxicity and improved outcomes in a wide variety of cancers. The purpose of this work is showing the results of left Chest-Wall knowledge-based planning (KBP) standardization and implementation in a LMIC setting.

MATERIALS/METHODS

A Halcyon Linac was installed at our clinic in Guatemala in 2019 and currently used to treat ∼90 IMRT patients daily. The standardization of IMRT procedures has been difficult for complex sites like chest-wall. The steps for standardization included: AAPM TG-263 nomenclature implementation, and planning workflows within the TPS, creation of optimization structures, and plan quality evaluation following RTOG1005 protocol hypofractionation arm. 25 plans were created manually achieving all RTOG1005 protocol constraints. The statistics were analyzed trough the model analytics tool provided by KPB manufacturer.

RESULTS

The results show that more plans are needed to improve the KBP model. This initial model was used to create a standardized clinical protocol in the TPS in order to continue adding plans to the KBP model database. This approach ensures that we obtain consistent plan quality and standardize our planning. The manual planning objectives achieved: CONCLUSION: The experience using the TPS to standardize our treatment planning process achieved good consistency in our planning objectives. This approach will help create KBP models according to our own clinic-specific requirements. Future work will be made to compare our LMIC KBP models with those made at a HIC academic radiotherapy center.

ARTIA-Bladder: Daily Online Adaptive Short-Course Radiation Therapy (RT) and Concurrent Chemotherapy for Muscle-Invasive Bladder Cancer (MIBC): A Prospective Trial of an Individualized Approach for Reducing Bowel and Bladder Toxicity

PURPOSE/OBJECTIVE(S)

Concurrent chemo-radiotherapy is commonly prescribed for muscle-invasive bladder cancer (MIBC). Post hoc analysis of two large, randomized trials found that hypofractionation improves loco-regional control (LRC) vs. standard fractionation in this population. A challenge in traditional image-guided radiotherapy of the bladder is that daily changes in bladder position and size requires large margins to ensure target coverage. This makes it difficult to spare uninvolved bladder from high-dose treatment, increases the risk of bowel toxicity, and results in historical rates of acute G3+ toxicity exceeding 20-30%. Daily online adaptive RT (ART) may enable reduced, personalized margins that maintain target coverage while reducing dose to OARs. This prospective clinical trial will test whether: 1) participants undergoing ART for MIBC have a lower rate of acute G3+ GI/GU toxicity compared with the 31% historical control rate (Stage III BC2001 trial), and 2) 2-year LRC with ART will be non-inferior to historical controls (75%).

MATERIALS/METHODS

This multi-national trial will enroll 165 adult subjects with stage cT2-T4aN0M0 urothelial MIBC. Subjects will have undergone an attempt at maximal transurethral resection of bladder tumor. Patients with clinically involved nodes or G2+ GI or G3+ GU symptoms/conditions at baseline are ineligible. Concurrent with chemotherapy, participants will receive (at the discretion of the investigator) either 55 Gy in 20 fx to whole-bladder or 46 Gy in 20 fx to whole-bladder plus simultaneous in-field boost of 55 Gy in 20 fx to tumor bed. A personalized ITV will be derived for each subject based on bladder expansion, as assessed on two CT simulations separated by 30 min. Daily ART will be attempted for all subjects. The primary endpoint is acute G3+ GI/GU toxicity. Secondary endpoints are LRC; quality of life (EORTC QLQ-BLM30, EPIC 26 bowel and urinary); global function (EQ-5D-5L ); 2-year disease-free, bladder intact event-free, and overall survival; 2-year bladder cancer-specific mortality; NTCP model of acute GI toxicity for hypofractionated bladder RT; workflow feasibility of ART; improved target coverage ± reduced dose to critical OARs vs. non-ART dosimetry; acute G3+ GI/GU toxicity rate in subjects with ≥75% of their treatments as ART; and acute G3+ GI/GU toxicity in the cohort treated with partial bladder boost. Exploratory translational and correlative endpoints will also be examined.

RESULTS

This trial opened to enrollment on Feb 2, 2023; the study duration is expected to be 4-5 years.

CONCLUSION

This prospective clinical trial will provide robust clinical data to inform healthcare providers' decisions on the use of daily online ART and hypofractionation as a bladder preservation strategy for this population.

Comparing Changes in Medicare Reimbursement for Radiation Oncology and Medical Oncology (2010-2020)

PURPOSE/OBJECTIVE(S)

A recent study found that radiation oncology (RO) has seen significant declines in Medicare reimbursement (MCR) from 2010-2019. While it is presumed that other cancer subspecialties have seen decreasing MCR, to our knowledge, there are no studies directly comparing changes in MCR between RO and other oncology subspecialties. In this study, we analyze changes in MCR from 2010-2020 for both RO and medical oncology. We hypothesized that the declines in MCR will be similar between the two fields.

MATERIALS/METHODS

The publicly available Physician/Supplier Procedure Summary (PSPS) database was used for all years from 2010-2020. All reimbursement for providers with primary provider codes 92 (RO) and 83 and 90 (heme/onc and medical oncology, respectively) were analyzed. For the 150 most highly-reimbursed HCPCS codes for each specialty in 2010, the total allowed charge for each code was corrected for inflation and then divided by the number of submitted claims to calculate average MCR per code for each year. For each code and each specialty, the 2020 billing frequency was multiplied by the calculated average reimbursement per claim in a given year to calculate what the reimbursement would have been in that year using 2020 dollars and utilization rates (projected reimbursement). The projected reimbursement was summed for all HCPCS codes in each year for each specialty to calculate an aggregate MCR for that specialty for that year. This aggregate MCR was then compared with the actual 2020 reimbursement for that basket of codes to calculate the change in MCR over time.

RESULTS

Both medical and radiation oncology saw decreases in projected vs. actual MCR from 2010-2020 for this basket of services (Table). Adjusting for inflation and utilization, RO MCR declined by $0.7 billion (B) (-29.0%) from 2010 to 2020 and by $0.2B (-10.5%) from 2015 to 2020 while medical oncology MCR declined by $0.8B (-14.7%) from 2010-2020 and by $0.4B (-6.6%) from 2015-2020. The average decrease per year in projected vs. actual reimbursement for RO was 2.9% (2010 to 2015) and 1.05% (2015 to 2020) and for medical oncology was 1.5% (2010-2015) and 0.7% (2015-2020), respectively.

CONCLUSION

Adjusting for inflation, Medicare reimbursement for a large array of services has declined for both medical oncology and RO from 2010 - 2020. Contrary to our hypothesis, RO reported a 97% greater relative decline in reimbursement compared with medical oncology from 2010 - 2020. Significant decreases in reimbursement to both fields and their potential implications on patient care and access to care should be considered by policymakers while shifting towards an episode-based Alternative Payment Model and when considering further cuts to Medicare reimbursement.

Long-Term Follow-Up Analysis of NRG Oncology RTOG 0415: A Randomized Phase III Non-Inferiority Study Comparing Two Fractionation Schedules in Patients with Favorable-Risk Prostate Cancer

PURPOSE/OBJECTIVE(S)

To assess whether the efficacy of a hypofractionated (H) schedule is no worse than a conventional (C) schedule in men with low-risk prostate cancer.

MATERIALS/METHODS

Accrual began April 2006 and ended in December 2009. 1115 men with favorable-risk prostate cancer were randomly assigned 1:1 to a conventional (C) schedule (73.8 Gy in 41 fractions over 8.2 weeks) or to a hypofractionated (H) schedule (70 Gy in 28 fractions over 5.6 weeks). The trial was designed to establish with 90% power and alpha = 0.05 that (H) results in 5-year disease-free survival (DFS) that is not lower than (C) by more than 7% (hazard ratio (HR) < 1.52). Protocol specified secondary endpoints evaluated for noninferiority include: biochemical recurrence (BR), local progression, disease-specific survival, and overall survival.

RESULTS

One thousand ninety-two protocol eligible men were analyzed: 542 to C and 550 to H. Median follow-up is 12.75 years. Baseline characteristics were not different according to treatment arm. The estimated 12-year DFS is 56.1% (95% CI 51.5, 60.5) in the C arm and 61.8% (57.2, 66.0) in the H arm. The DFS hazard ratio (H/C) is 0.85 (0.71-1.03), confirming non-inferiority (p<0.001). Twelve-year cumulative incidence of biochemical recurrence (BR) was 17.0% (CI 13.8, 20.5) in the C-RT and 9.9% (CI 7.5, 12.6) in the H-RT arm; (HR = 0.56, (0.40-0.78) suggesting improved efficacy with H. Additional pre-specified secondary endpoints were non-inferior Late Grade ≥ 3 GI toxicity is 3.2% (C) vs. 4.4% (H), Relative risk (RR) for H vs. C 1.39 (CI 0.75, 2.55) Late Grade ≥ 3 GU toxicity is 3.4% (C) vs. 4.2% (H), RR = 1.26 (CI 0.69, 2.30).

CONCLUSION

In men with favorable-risk prostate cancer, long-term disease-free survival is non-inferior with 70 Gy in 28 fractions compared to 73.8 Gy in 41 fractions. The risk of BR is reduced with moderate hypofractionation. No differences in late Grade ≥3 GI/GU toxicity were observed between the arms. (ClinicalTrials.gov identifier: NCT00331773).

Quality of Life Results of Addition of Androgen Deprivation Therapy and Pelvic Lymph Node Treatment to Prostate Bed Salvage Radiotherapy: NRG Oncology/RTOG 0534 SPPORT

PURPOSE/OBJECTIVE(S)

Report the quality of life (QOL) analysis of the SPPORT trial of men with a detectable prostate specific antigen (PSA) after prostatectomy for prostate cancer randomized to (Arm 1) salvage prostate bed radiotherapy (PBRT), (Arm 2) 4-6 months of short-term androgen deprivation therapy (STADT) + PBRT, and (Arm 3) pelvic lymph node radiotherapy (PLNRT) + STADT + PBRT. Primary analysis established a benefit of adding PLNRT and STADT to PBRT. There was higher short term but no statistically significant difference in long term adverse events with the exception of blood or bone marrow events.

MATERIALS/METHODS

QOL endpoints were assessed at baseline, 6 weeks after RT start, 1 and 5 years, including Expanded Prostate Cancer Index Composite (EPIC) (bowel, urinary, sexual, and hormonal domains), Hopkins Symptom Checklist (HSCL-25) (depressive symptoms), and the EuroQol (EQ-5D) (health state weights used in quality adjusted life years (QALYs). In addition to statistical significance, differences in scores were assessed using 0.5 standard deviation (SD) as the criterion for clinical importance. Difference among arms was assessed using pairwise t-tests, Fisher's exact test, and mixed effects regression modeling. To control for multiplicity, the p-value required for statistical significance is p<0.025.

RESULTS

Six hundred forty-four patients consented to QOL, about 210 on each arm. Baseline characteristics were not significantly different among arms: 81% were white and 54% <65 years. For EPIC, bowel domain scores decreased at 6 weeks post-RT then increased by years 1 and 5, although not to baseline levels. One clinically significant difference in bowel scores was Arm 3 vs. Arm 1 at 6 weeks. For the urinary domain, scores decreased at 6 weeks post-RT and remained below baseline at 1 and 5 years, but there were no significant differences among arms. For the sexual domain, there were statistically significant differences between arms at 6 weeks and 1 year with patients receiving STADT exhibiting poorer sexual QOL scores. By year 5 the differences were no longer significant. A similar pattern was seen for the hormonal domain. For HSCL-25, differences at 6 weeks were statistically but not clinically significant, and there were no significant differences at the later time points. Comparisons of QALYs for overall survival over an 8-year horizon showed no significant group differences, with a mean of about 7.8 in each arm. Regarding freedom from progression, QALY means were 5.7, 6.5, and 7.4 years for Arms 1, 2, and 3, respectively, with a significant difference between Arms 3 and 1 (p = <.001) favoring the more intensive treatment.

CONCLUSION

While QOL generally declined among all arms at 6 weeks post RT, there were no clinically significant differences in QOL among arms at 5 years. QALYs for freedom from progression favored STADT + PLNRT + PBRT for salvage treatment of prostate cancer.

Effect of Brachytherapy With External Beam Radiation Therapy Versus Brachytherapy Alone for Intermediate-Risk Prostate Cancer: NRG Oncology RTOG 0232 Randomized Clinical Trial

PURPOSE

To determine whether addition of external beam radiation therapy (EBRT) to brachytherapy (BT) (COMBO) compared with BT alone would improve 5-year freedom from progression (FFP) in intermediate-risk prostate cancer.

METHODS

Men with prostate cancer stage cT1c-T2bN0M0, Gleason Score (GS) 2-6 and prostate-specific antigen (PSA) 10-20 or GS 7, and PSA < 10 were eligible. The COMBO arm was EBRT (45 Gy in 25 fractions) to prostate and seminal vesicles followed by BT prostate boost (110 Gy if 125-Iodine, 100 Gy if 103-Pd). BT arm was delivered to prostate only (145 Gy if 125-Iodine, 125 Gy if 103-Pd). The primary end point was FFP: PSA failure (American Society for Therapeutic Radiology and Oncology [ASTRO] or Phoenix definitions), local failure, distant failure, or death.

RESULTS

Five hundred eighty-eight men were randomly assigned; 579 were eligible: 287 and 292 in COMBO and BT arms, respectively. The median age was 67 years; 89.1% had PSA < 10 ng/mL, 89.1% had GS 7, and 66.7% had T1 disease. There were no differences in FFP. The 5-year FFP-ASTRO was 85.6% (95% CI, 81.4 to 89.7) with COMBO compared with 82.7% (95% CI, 78.3 to 87.1) with BT (odds ratio [OR], 0.80; 95% CI, 0.51 to 1.26; Greenwood T P = .18). The 5-year FFP-Phoenix was 88.0% (95% CI, 84.2 to 91.9) with COMBO compared with 85.5% (95% CI, 81.3 to 89.6) with BT (OR, 0.80; 95% CI, 0.49 to 1.30; Greenwood T P = .19). There were no differences in the rates of genitourinary (GU) or GI acute toxicities. The 5-year cumulative incidence for late GU/GI grade 2+ toxicity is 42.8% (95% CI, 37.0 to 48.6) for COMBO compared with 25.8% (95% CI, 20.9 to 31.0) for BT (P < .0001). The 5-year cumulative incidence for late GU/GI grade 3+ toxicity is 8.2% (95% CI, 5.4 to 11.8) compared with 3.8% (95% CI, 2.0 to 6.5; P = .006).

CONCLUSION

Compared with BT, COMBO did not improve FFP for prostate cancer but caused greater toxicity. BT alone can be considered as a standard treatment for men with intermediate-risk prostate cancer.

Androgen Deprivation and Radiotherapy with or Without Docetaxel for Localized High-risk Prostate Cancer: Long-term Follow-up from the Randomized NRG Oncology RTOG 0521 Trial

BACKGROUND

Intensification of therapy may improve outcomes for patients with high-risk localized prostate cancer.

OBJECTIVE

To provide long-term follow-up data from phase III RTOG 0521, which compared a combination of androgen deprivation therapy (ADT) + external beam radiation therapy (EBRT) + docetaxel with ADT + EBRT.

DESIGN, SETTING, AND PARTICIPANTS

High-risk localized prostate cancer patients (>50% of patients had Gleason 9-10 disease) were prospectively randomized to 2 yr of ADT + EBRT or ADT + EBRT + six cycles of docetaxel. A total of 612 patients were accrued, and 563 were eligible and included in the modified intent-to-treat analysis.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary endpoint was overall survival (OS). Analyses with Cox proportional hazards were performed as prespecified in the protocol; however, there was evidence of nonproportional hazards. Thus, a post hoc analysis was performed using the restricted mean survival time (RMST). The secondary endpoints included biochemical failure, distant metastasis (DM) as detected by conventional imaging, and disease-free survival (DFS).

RESULTS AND LIMITATIONS

After 10.4 yr of median follow-up among survivors, the hazard ratio (HR) for OS was 0.89 (90% confidence interval [CI] 0.70-1.14; one-sided log-rank p = 0.22). Survival at 10 yr was 64% for ADT + EBRT and 69% for ADT + EBRT + docetaxel. The RMST at 12 yr was 0.45 yr and not statistically significant (one-sided p = 0.053). No differences were detected in the incidence of DFS (HR = 0.92, 95% CI 0.73-1.14), DM (HR = 0.84, 95% CI 0.73-1.14), or prostate-specific antigen recurrence risk (HR = 0.97, 95% CI 0.74-1.29). Two patients had grade 5 toxicity in the chemotherapy arm and zero patients in the control arm.

CONCLUSIONS

After a median follow-up of 10.4 yr among surviving patients, no significant differences are observed in clinical outcomes between the experimental and control arms. These data suggest that docetaxel should not be used for high-risk localized prostate cancer. Additional research may be warranted using novel predictive biomarkers.

PATIENT SUMMARY

No significant differences in survival were noted after long-term follow-up for high-risk localized prostate cancer patients in a large prospective trial where patients were treated with androgen deprivation therapy + radiation to the prostate ± docetaxel.

Five-Year Patient-Reported Outcomes in NRG Oncology RTOG 0938, Evaluating Two Ultrahypofractionated Regimens for Prostate Cancer

PURPOSE

There is considerable interest in very short (ultrahypofractionated) radiation therapy regimens to treat prostate cancer based on potential radiobiological advantages, patient convenience, and resource allocation benefits. Our objective is to demonstrate that detectable changes in health-related quality of life measured by the bowel and urinary domains of the Expanded Prostate Cancer Index Composite (EPIC-50) were not substantially worse than baseline scores.

METHODS AND MATERIALS

NRG Oncology's RTOG 0938 is a nonblinded randomized phase 2 study of National Comprehensive Cancer Network low-risk prostate cancer in which each arm is compared with a historical control. Patients were randomized to 5 fractions (7.25 Gy in 2 week and a day [twice a week]) or 12 fractions (4.3Gy in 2.5 weeks [5 times a week]). Secondary objectives assessed patient-reported toxicity at 5 years using the EPIC. Chi-square tests were used to assess the proportion of patients with a deterioration from baseline of >5 points for bowel, >2 points for urinary, and >11 points for sexual score.

RESULTS

The study enrolled 127 patients to 5 fractions (121 eligible) and 128 patients to 12 fractions (125 eligible). The median follow-up for all patients at the time of analysis was 5.38 years. The 5-year frequency for >5 point change in bowel score were 38.4% (P = .27) and 23.4% (P = 0.98) for 5 and 12 fractions, respectively. The 5-year frequencies for >2 point change in urinary score were 46.6% (P = .15) and 36.4% (P = .70) for 5 and 12 fractions, respectively. For 5 fractions, 49.3% (P = .007) of patients had a drop in 5-year EPIC-50 sexual score of ≥11 points; for 12 fractions, 54% (P < .001) of patients had a drop in 5-year EPIC-50 sexual score of ≥11 points. Disease-free survival at 5 years is 89.6% (95% CI: 84.0-95.2) in the 5-fraction arm and 92.3% (95% CI: 87.4-97.1) in the 12-fraction arm. There was no late grade 4 or 5 treatment-related urinary or bowel toxicity.

CONCLUSIONS

This study confirms that, based on long-term changes in bowel and urinary domains and toxicity, the 5- and 12-fraction regimens are well tolerated. These ultrahypofractionated approaches need to be compared with current standard radiation therapy regimens.

Dose-Escalated Radiotherapy Alone or in Combination With Short-Term Androgen Deprivation for Intermediate-Risk Prostate Cancer: Results of a Phase III Multi-Institutional Trial

PURPOSE

It remains unknown whether or not short-term androgen deprivation (STAD) improves survival among men with intermediate-risk prostate cancer (IRPC) treated with dose-escalated radiotherapy (RT).

METHODS

The NRG Oncology/Radiation Therapy Oncology Group 0815 study randomly assigned 1,492 patients with stage T2b-T2c, Gleason score 7, or prostate-specific antigen (PSA) value >10 and ≤20 ng/mL to dose-escalated RT alone (arm 1) or with STAD (arm 2). STAD was 6 months of luteinizing hormone-releasing hormone agonist/antagonist therapy plus antiandrogen. RT modalities were external-beam RT alone to 79.2 Gy or external beam (45 Gy) with brachytherapy boost. The primary end point was overall survival (OS). Secondary end points included prostate cancer-specific mortality (PCSM), non-PCSM, distant metastases (DMs), PSA failure, and rates of salvage therapy.

RESULTS

Median follow-up was 6.3 years. Two hundred nineteen deaths occurred, 119 in arm 1 and 100 in arm 2. Five-year OS estimates were 90% versus 91%, respectively (hazard ratio [HR], 0.85; 95% CI, 0.65 to 1.11]; P = .22). STAD resulted in reduced PSA failure (HR, 0.52; P <.001), DM (HR, 0.25; P <.001), PCSM (HR, 0.10; P = .007), and salvage therapy use (HR, 0.62; P = .025). Other-cause deaths were not significantly different (P = .56). Acute grade ≥3 adverse events (AEs) occurred in 2% of patients in arm 1 and in 12% for arm 2 (P <.001). Cumulative incidence of late grade ≥3 AEs was 14% in arm 1 and 15% in arm 2 (P = .29).

CONCLUSION

STAD did not improve OS rates for men with IRPC treated with dose-escalated RT. Improvements in metastases rates, prostate cancer deaths, and PSA failures should be weighed against the risk of adverse events and the impact of STAD on quality of life.

Neighborhood Deprivation and Rurality Associated With Patient-Reported Outcomes and Survival in Men With Prostate Cancer in NRG Oncology RTOG 0415

PURPOSE

Rurality and neighborhood deprivation can contribute to poor patient-reported outcomes, which have not been systematically evaluated in patients with specific cancers in national trials. Our objective was to examine the effect of rurality and neighborhood socioeconomic and environmental deprivation on patient-reported outcomes and survival in men with prostate cancer in NRG Oncology RTOG 0415.

METHODS AND MATERIALS

Data from men with prostate cancer in trial NRG Oncology RTOG 0415 were analyzed; 1,092 men were randomized to receive conventional radiation therapy or hypofractionated radiation therapy. Rurality was categorized as urban or rural. Neighborhood deprivation was assessed using the area deprivation index and air pollution indicators (nitrogen dioxide and particulate matter with a diameter less than 2.5 micrometers) via patient ZIP codes. Expanded Prostate Cancer Index Composite measured cancer-specific quality of life. The Hopkins symptom checklist measured anxiety and depression. EuroQoL-5 Dimension assessed general health.

RESULTS

We analyzed 751 patients in trial NRG Oncology RTOG 0415. At baseline, patients from the most deprived neighborhoods had worse bowel (P = .011), worse sexual (P = .042), and worse hormonal (P = .015) scores; patients from the most deprived areas had worse self-care (P = .04) and more pain (P = .047); and patients from rural areas had worse urinary (P = .03) and sexual (P = .003) scores versus patients from urban areas. Longitudinal analyses showed that the 25% most deprived areas (P = .004) and rural areas (P = .002) were associated with worse EuroQoL-5 Dimension visual analog scale score. Patients from urban areas (hazard ratio, 1.81; P = .033) and the 75% less-deprived neighborhoods (hazard ratio, 0.68; P = .053) showed relative decrease in risk of recurrence or death (disease-free survival).

CONCLUSIONS

Patients with prostate cancer from the most deprived neighborhoods and rural areas had low quality of life at baseline, poor general health longitudinally, and worse disease-free survival. Interventions should screen populations from deprived neighborhoods and rural areas to improve patient access to supportive care services.

Dose-Escalated Radiation Alone or in Combination With Short-Term Total Androgen Suppression for Intermediate-Risk Prostate Cancer: Patient-Reported Outcomes From NRG/Radiation Therapy Oncology Group 0815 Randomized Trial

PURPOSE

To report patient-reported outcomes (PROs) of a phase III trial evaluating total androgen suppression (TAS) combined with dose-escalated radiation therapy (RT) for patients with intermediate-risk prostate cancer.

METHODS

Patients with intermediate-risk prostate cancer were randomly assigned to dose-escalated RT alone (arm 1) or RT plus TAS (arm 2) consisting of luteinizing hormone-releasing hormone agonist/antagonist with oral antiandrogen for 6 months. The primary PRO was the validated Expanded Prostate Cancer Index Composite (EPIC-50). Secondary PROs included Patient-Reported Outcome Measurement Information System (PROMIS)-fatigue and EuroQOL five-dimensions scale questionnaire (EQ-5D). PRO change scores, calculated for each patient as the follow-up score minus baseline score (at the end of RT and at 6, 12, and 60 months), were compared between treatment arms using a two-sample t test. An effect size of 0.50 standard deviation was considered clinically meaningful.

RESULTS

For the primary PRO instrument (EPIC), the completion rates were ≥86% through the first year of follow-up and 70%-75% at 5 years. For the EPIC hormonal and sexual domains, there were clinically meaningful (P < .0001) deficits in the RT + TAS arm. However, there were no clinically meaningful differences by 1 year between arms. There were also no clinically meaningful differences at any time points between arms for PROMIS-fatigue, EQ-5D, and EPIC bowel/urinary scores.

CONCLUSION

Compared with dose-escalated RT alone, adding TAS demonstrated clinically meaningful declines only in EPIC hormonal and sexual domains. However, even these PRO differences were transient, and there were no clinically meaningful differences between arms by 1 year.

Logistical, technical, and radiation safety aspects of establishing a radiopharmaceutical therapy program: A case in Lutetium-177 prostate-specific membrane antigen (PSMA) therapy

Prostate-specific membrane antigen (PSMA) is a cell surface protein highly expressed in nearly all prostate cancers, with restricted expression in some normal tissues. The differential expression of PSMA from tumor to non-tumor tissue has resulted in the investigation of numerous targeting strategies for therapy of patients with metastatic prostate cancer. In March of 2022, the FDA granted approval for the use of lutetium-177 PSMA-617 (Lu-177-PSMA-617) for patients with PSMA-positive metastatic castration-resistant prostate cancer (mCRPC) who have been treated with androgen receptor pathway inhibition and taxane-based chemotherapy. Therefore, the use of Lu-177-PSMA-617 is expected to increase and become more widespread. Herein, we describe logistical, technical, and radiation safety considerations for implementing a radiopharmaceutical therapy program, with particular focus on the development of operating procedures for therapeutic administrations. Major steps for a center in the U.S. to implement a new radiopharmaceutical therapy (RPT) program are listed below, and then demonstrated in greater detail via examples for Lu-177-PSMA-617 therapy.

Body composition and mortality in men receiving prostate radiotherapy: A pooled analysis of NRG/RTOG 9406 and NRG/RTOG 0126

PURPOSE

To validate the association between body composition and mortality in men treated with radiation for localized prostate cancer (PCa). Secondarily, to integrate body composition as a factor to classify patients by risk of all-cause mortality.

MATERIALS AND METHODS

Participants of NRG/Radiation Therapy Oncology Group (RTOG) 9406 and NRG/RTOG 0126 with archived computed tomography were included. Muscle mass and muscle density were estimated by measuring the area and attenuation of the psoas muscles on a single slice at L4-L5. Bone density was estimated by measuring the attenuation of the vertebral body at mid-L5. Survival analyses, including Cox proportional hazards models, assessed the relationship between body composition and mortality. Recursive partitioning analysis (RPA) was used to create a classification tree to classify participants by risk of death.

RESULTS

Data from 2066 men were included in this study. In the final multivariable model, psoas area, comorbidity score, baseline prostate serum antigen, and age were significantly associated with survival. The RPA yielded a classification tree with four prognostic groups determined by age, comorbidity, and psoas area. Notably, the classification among older (≥70 years) men into prognostic groups was determined by psoas area.

CONCLUSIONS

This study strongly supports that body composition is related to mortality in men with localized PCa. The inclusion of psoas area in the RPA classification tree suggests that body composition provides additive information to age and comorbidity status for mortality prediction, particularly among older men. More research is needed to determine the clinical impact of body composition on prognostic models in men with PCa.

Biochemical recurrence (BCR) surrogacy for clinical outcomes after radiotherapy for adenocarcinoma of the prostate (BCRSCRAP): A meta-analysis from MARCAP Consortium

391

Background: Event-free survival, a PSA-driven endpoint, was shown to not be surrogate endpoint for overall survival (OS) in the ICECAP two-stage meta-analytic approach. However, time to biochemical recurrence (TTBCR) in NRG/RTOG 9202 met Prentice criteria for surrogacy. We performed an individual patient data (IPD) meta-analysis of 11 randomized controlled trials evaluating RT dose escalation, ADT use, and adjuvant ADT prolongation to evaluate the surrogacy of time to BCR (TTBCR), censoring for non-prostate cancer deaths, using both approaches to evaluate surrogacy. Methods: This individual patient level meta-analysis was performed using data from the MARCAP consortium, and 11 radiotherapy trials were included. TTBCR was defined as time to developing a BCR or experiencing prostate cancer-specific mortality (PCSM), with censoring at time of other-cause death or loss to follow-up. Landmark analyses were used to test the Prentice criteria for surrogacy. For patient level correlation between TTBCR and OS, we applied a bivariate Copula model to estimate the Kendall’s τ. For trial level correlation of the treatment effect on TTBCR and true endpoints, a weighted linear regression model was applied between the effects of treatment (natural log of hazard ratio [log-HR]) on OS versus TTBCR using a weightage that was inverse variance of BCR log-HR estimate. Results: Based on Prentice criteria, BCR at the landmark time point of 48 months was associated with increased risk of mortality in trials that compared treatment intensification with adjuvant ADT prolongation (HR 2.18 [95% CI 1.95-2.42]), the addition of ADT (HR 1.38 [1.25-1.54]), and RT dose escalation (HR 2.12 [1.83-2.46]) on uni- and multi-variable analyses. At the patient level, there was a low to moderate level correlation between BCR and OS with Kendall’s τ of 0.34 and a R2 of 0.55 for correlation of treatment effect on TTBCR and OS. At the trial level, there was a poor correlation between treatment effect on TTBCR and OS (R2=0.16). Conclusions: This IPD meta-analysis demonstrates that while BCR is prognostic, it is not a surrogate endpoint for OS in localized prostate cancer for patients treated with a diverse array of radiotherapeutic strategies. This highlights the importance of other cause mortality in prostate cancer. Our results highlight the differences in interpretability of Prentice criteria and the two-stage meta-analytic approach and suitability of endpoints for clinical trial design.

The Association of Radiation Dose With Overall Survival for Patients Treated With Prostate Stereotactic Body Radiation Therapy

Introduction Stereotactic body radiation therapy (SBRT) for prostate adenocarcinoma (PCa) has demonstrated excellent biochemical recurrence-free survival, with studies showing improved BRFS with higher-dose SBRT. However, current studies have been underpowered to evaluate the relationship of SBRT dose to overall survival (OS). In this retrospective study using the National Cancer Database (NCDB), we hypothesize that, given the low alpha/beta ratio of PCa, a relatively small increase in the dose-per-fraction would be associated with improved survival outcomes for intermediate-risk PCa (IR-PCa) comparing 36.25 Gy/5 fx [biologically equivalent dose (BEDα/β = 1.5 = 211.46 Gy vs. 35 Gy (BED1.5 = 198.33 Gy)]. Materials and methods We queried records from the NCDB from 2005 to 2015 for men receiving prostate SBRT for IR-PCa (n=2673). 82% were treated using either 35 Gy/5 fx or 36.25 Gy/5 fx. We compared OS in men receiving 35 Gy versus 36.25 Gy. Inverse probability of treatment weighting (IPTW) was used to adjust for covariable imbalances. Unweighted- and weighted-multivariable analysis (MVA) using Cox regression was used to compare OS hazard ratios, accounting for age, race, Charlson-Deyo comorbidity score, treatment facility type, prostate-specific antigen (PSA), clinical T-stage, Gleason Score, and use of androgen deprivation therapy (ADT). Kaplan-Meier analysis was performed. Results Seven hundred and eighty men (35%) were treated with 35 Gy/5 fx and 1434 men (65%) were treated with 36.25 Gy/5 fx (n=2214). Compared to 35 Gy, treatment with 36.25 Gy was associated with significantly improved OS (hazard ratio [HR]: 0.61 [95% CI: 0.43-0.89], P=0.009) on MVA. On Kaplan-Meier analysis, 36.25 Gy was associated with improved survival (p=0.034), with a five-year OS of 92% and 88%, respectively. Conclusions In a multi-institutional retrospective database of 2,214 IR patients treated with prostate SBRT, a prescription dose of 36.25 Gy/5 fx was associated with improved OS vs. 35 Gy/5 fx. Results are hypothesis-generating but do lend support to the current National Comprehensive Cancer Network (NCCN) guidelines that the minimum recommended dose for prostate SBRT is 36.25 Gy/5 fx.

An Analysis of Major Target Deviations in Craniospinal Irradiation Treatment Plans for Patients With Intermediate-Risk Medulloblastoma Within a Phase 3 Clinical Trial (Children's Oncology Group Study ACNS0331)

Purpose

Craniospinal irradiation remains an essential and yet difficult part of the treatment of patients with medulloblastoma. Whereas technological advances offer promise of increased conformity, realiance on advanced technology is not without risk, and it remains critical to carefully delineate targets. We describe examples of target deviations (TDs) in craniospinal irradiation treatment plans for postoperative patients with medulloblastoma in a phase 3 clinical trial (ACNS 0331).

Methods and Materials

The principal investigator independently performed a review of the treatment plans and portal films of enrolled patients and evaluated the plans for TDs. TDs of dose, dose uniformity, and volume were defined as major or minor deviations. Major TDs scored as protocol violations. The effect of major TDs on event-free survival (EFS) and overall survival (OS) was evaluated using the stratified Cox proportional hazards model.

Results

Of the 549 patients enrolled, 461 were available for this analysis. Thirty-two (7%) plans did not have data sufficient for TD evaluation. Major TDs were found in 32 of the 461 plans (7%). Of those, 21 were deviations of target volume alone, 7 were deviations of target dose alone, and 4 were deviations of both target volume and dose. The 25 patients with TDs of volume involved 29 sites. The most common major TDs of volume involved the brain (9 of 29) and the posterior fossa (9 of 29). On Cox proportional hazards modeling, the presence of a major TD did not statistically significantly affect EFS (hazard ratio, 0.98; 95% confidence interval, 0.45-2.11; P = .9541) or OS (hazard ratio, 1.10; 95% confidence interval, 0.51-2.38; P = .8113).

Conclusions

Although intensity modulated radiation therapy and proton therapy are promising in improving conformity and sparing organs at risk, technology does not substitute for careful anatomic definition of target volumes. The study was not powered to evaluate the effect of TDs on EFS and OS; therefore, the statistical analysis presented in this study must be interpreted with caution.

Local Failure Events in Prostate Cancer Treated with Radiotherapy: A Pooled Analysis of 18 Randomized Trials from the Meta-analysis of Randomized Trials in Cancer of the Prostate Consortium (LEVIATHAN)

CONTEXT

The prognostic importance of local failure after definitive radiotherapy (RT) in National Comprehensive Cancer Network intermediate- and high-risk prostate cancer (PCa) patients remains unclear.

OBJECTIVE

To evaluate the prognostic impact of local failure and the kinetics of distant metastasis following RT.

EVIDENCE ACQUISITION

A pooled analysis was performed on individual patient data of 12 533 PCa (6288 high-risk and 6245 intermediate-risk) patients enrolled in 18 randomized trials (conducted between 1985 and 2015) within the Meta-analysis of Randomized Trials in Cancer of the Prostate Consortium. Multivariable Cox proportional hazard (PH) models were developed to evaluate the relationship between overall survival (OS), PCa-specific survival (PCSS), distant metastasis-free survival (DMFS), and local failure as a time-dependent covariate. Markov PH models were developed to evaluate the impact of specific transition states.

EVIDENCE SYNTHESIS

The median follow-up was 11 yr. There were 795 (13%) local failure events and 1288 (21%) distant metastases for high-risk patients and 449 (7.2%) and 451 (7.2%) for intermediate-risk patients, respectively. For both groups, 81% of distant metastases developed from a clinically relapse-free state (cRF state). Local failure was significantly associated with OS (hazard ratio [HR] 1.17, 95% confidence interval [CI] 1.06-1.30), PCSS (HR 2.02, 95% CI 1.75-2.33), and DMFS (HR 1.94, 95% CI 1.75-2.15, p < 0.01 for all) in high-risk patients. Local failure was also significantly associated with DMFS (HR 1.57, 95% CI 1.36-1.81) but not with OS in intermediate-risk patients. Patients without local failure had a significantly lower HR of transitioning to a PCa-specific death state than those who had local failure (HR 0.32, 95% CI 0.21-0.50, p < 0.001). At later time points, more distant metastases emerged after a local failure event for both groups.

CONCLUSIONS

Local failure is an independent prognosticator of OS, PCSS, and DMFS in high-risk and of DMFS in intermediate-risk PCa. Distant metastasis predominantly developed from the cRF state, underscoring the importance of addressing occult microscopic disease. However a "second wave" of distant metastases occurs subsequent to local failure events, and optimization of local control may reduce the risk of distant metastasis.

PATIENT SUMMARY

Among men receiving definitive radiation therapy for high- and intermediate-risk prostate cancer, about 10% experience local recurrence, and they are at significantly increased risks of further disease progression. About 80% of patients who develop distant metastasis do not have a detectable local recurrence preceding it.

The Influence of the Pretreatment Immune State on Response to Radiation Therapy in High-Risk Prostate Cancer: A Validation Study From NRG/RTOG 0521

PURPOSE

The immunoinflammatory state has been shown to be associated with poor outcomes after radiation therapy (RT). We conducted an a priori designed validation study using serum specimens from Radiation Therapy Oncology Group (RTOG) 0521. It was hypothesized the pretreatment inflammatory state would correlate with clinical outcomes.

METHODS AND MATERIALS

Patients on RTOG 0521 had serum banked for biomarker validation. This study was designed to validate previous findings showing an association between elevations in C-reactive protein (CRP) and shorter biochemical disease free survival (bDFS). CRP levels were measured in pretreatment samples. An exploratory panel of related cytokines was also measured including: monocyte chemotactic protein-1, granulocyte-macrophage colony-stimulating factor, interferon-γ, interleukin (IL)-1b, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, IL-13, IL-17A, IL-23, and tumor necrosis factor. The primary endpoint examined was bDFS. Additional exploratory endpoints included overall survival, distant metastases, and toxicity events attributed to RT.

RESULTS

Two hundred and two patients in RTOG/NRG 0521 had serum samples available. Median age was 66 years (48-83), and 90% of patients were White. There was not an association between CRP and bDFS (adjusted hazard ratio [HR], 1.07 per 1 log increase in CRP; 95% confidence interval, 0.83-1.38; P = .60). In the exploratory, unplanned analysis, pretreatment IL-10 was significantly associated with worse bDFS (adjusted HR, 1.61 per log increase; P = .0027) and distant metastases (HR, 1.55 per log increase; P = .028). The association of IL-10 with bDFS was maintained on a multiplicity adjustment. The exploratory analyses of pretreatment levels of interferon-γ, IL-1b, IL-2, IL-13, IL-23 were negatively associated with grade 2 or higher pollakiuria (adjusted odds ratio, 0.64, 0.65, 0.71, 0.72, and 0.74, respectively, all P < .05), and IL-6 was negatively associated with grade 2 or higher erectile dysfunction (odds ratio, 0.62; P = .027).

CONCLUSIONS

Pretreatment CRP was not associated with a poorer bDFS after RT. In a hypothesis- generating analysis, higher baseline levels of IL-10 were associated with lower rates of bDFS. These findings require additional prospective evaluation.

High-dose Radiotherapy or Androgen Deprivation Therapy (HEAT) as Treatment Intensification for Localized Prostate Cancer: An Individual Patient-data Network Meta-analysis from the MARCAP Consortium

BACKGROUND

The relative benefits of radiotherapy (RT) dose escalation and the addition of short-term or long-term androgen deprivation therapy (STADT or LTADT) in the treatment of prostate cancer are unknown.

OBJECTIVE

To perform a network meta-analysis (NMA) of relevant randomized trials to compare the relative benefits of RT dose escalation ± STADT or LTADT.

DESIGN, SETTING, AND PARTICIPANTS

An NMA of individual patient data from 13 multicenter randomized trials was carried out for a total of 11862 patients. Patients received one of the six permutations of low-dose RT (64 to <74 Gy) ± STADT or LTADT, high-dose RT (≥74 Gy), or high-dose RT ± STADT or LTADT.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSES

Metastasis-free survival (MFS) was the primary endpoint. Frequentist and Bayesian NMAs were performed to rank the various treatment strategies by MFS and biochemical recurrence-free survival (BCRFS).

RESULTS AND LIMITATIONS

Median follow-up was 8.8 yr (interquartile range 5.7-11.5). The greatest relative improvement in outcomes was seen for addition of LTADT, irrespective of RT dose, followed by addition of STADT, irrespective of RT dose. RT dose escalation did not improve MFS either in the absence of ADT (hazard ratio [HR] 0.97, 95% confidence interval [CI] 0.80-1.18) or with STADT (HR 0.99, 95% CI 0.8-1.23) or LTADT (HR 0.94, 95% CI 0.65-1.37). According to P-score ranking and rankogram analysis, high-dose RT + LTADT was the optimal treatment strategy for both BCRFS and longer-term outcomes.

CONCLUSIONS

Conventionally escalated RT up to 79.2 Gy, alone or in the presence of ADT, does not improve MFS, while addition of STADT or LTADT to RT alone, regardless of RT dose, consistently improves MFS. RT dose escalation does provide a high probability of improving BCRFS and, provided it can be delivered without compromising quality of life, may represent the optimal treatment strategy when used in conjunction with ADT.

PATIENT SUMMARY

Using a higher radiotherapy dose when treating prostate cancer does not reduce the chance of developing metastases or death, but it does reduce the chance of having a rise in prostate-specific antigen (PSA) signifying recurrence of cancer. Androgen deprivation therapy improves all outcomes. A safe increase in radiotherapy dose in conjunction with androgen deprivation therapy may be the optimal treatment.

Prostate cancer therapy personalization via multi-modal deep learning on randomized phase III clinical trials

Prostate cancer is the most frequent cancer in men and a leading cause of cancer death. Determining a patient's optimal therapy is a challenge, where oncologists must select a therapy with the highest likelihood of success and the lowest likelihood of toxicity. International standards for prognostication rely on non-specific and semi-quantitative tools, commonly leading to over- and under-treatment. Tissue-based molecular biomarkers have attempted to address this, but most have limited validation in prospective randomized trials and expensive processing costs, posing substantial barriers to widespread adoption. There remains a significant need for accurate and scalable tools to support therapy personalization. Here we demonstrate prostate cancer therapy personalization by predicting long-term, clinically relevant outcomes using a multimodal deep learning architecture and train models using clinical data and digital histopathology from prostate biopsies. We train and validate models using five phase III randomized trials conducted across hundreds of clinical centers. Histopathological data was available for 5654 of 7764 randomized patients (71%) with a median follow-up of 11.4 years. Compared to the most common risk-stratification tool-risk groups developed by the National Cancer Center Network (NCCN)-our models have superior discriminatory performance across all endpoints, ranging from 9.2% to 14.6% relative improvement in a held-out validation set. This artificial intelligence-based tool improves prognostication over standard tools and allows oncologists to computationally predict the likeliest outcomes of specific patients to determine optimal treatment. Outfitted with digital scanners and internet access, any clinic could offer such capabilities, enabling global access to therapy personalization.

MEDB-69. Clinical and molecular meta-analysis of three major medulloblastoma clinical trials (ACNS0331, SJMB03, ACNS0332) uncovers novel strategies to improve risk-stratified therapy

BACKGROUND: Given the vast molecular heterogeneity present within medulloblastoma (MB) and considerable differences in therapy, we performed a meta-analysis of three large, recently published, prospective clinical trials (ACNS0331, SJMB03, ACNS0332) comprising 898 children with newly-diagnosed MB to shape future therapy.

METHODS: Molecular subgroups, subtypes, and copy number variations were uniformly procured from DNA methylation profiles and mutations from next-generation sequencing. Patients were stratified into six clinically homogeneous groups for cross-trial comparisons: (1) ACNS0331_LDCSI - patients with non-metastatic (M0), non-residual (R0), non-anaplastic MB treated with low-dose (LD) craniospinal irradiation(CSI); (2) ACNS0331_SDCSI - patients with M0R0 non-anaplastic MB treated with standard-dose(SD) CSI; (3) SJMB03_SDCSI - patients with M0R0 non-anaplastic MB treated with SDCSI; (4) SJMB03_HDCSI - patients with metastatic (M+) MB treated with high-dose (HD) CSI; (5) ACNS0332_HDCSI - patients with M+ MB treated with HDCSI; (6) ACNS0332_HDCSI_Carbo - patients with M+ MB treated with HDCSI and carboplatin.

RESULTS: 803 (WNT=125, SHH=122, G3=189, G4=367) of 898 patients formed the cohort. No significant difference was observed between the event-free survival (EFS) from ACNS0331_SDCSI and SJMB03_SDCSI or from SJMB03_HDCSI and ACNS0332_HDCSI when analyzed as a whole or by subgroup. ACNS0331_LDCSI outcome was inferior to the combined ACNS0331_SDCSI + SJMB03_SDCSI cohorts (p<0.001) and in G3 (p=0.030). ACNS0332_HDCSI_Carbo EFS was superior to ACNS0332_HDCSI + SJMB03_HDCSI only in G3/G4_subtype III (p=0.045). Additional molecular risk factor analysis identified M0R0 G3/G4_subtype VII and SHH without high-risk features as very low risk (>90% EFS) and M0R0 G3/G4_subtype III as high risk (<40% EFS).

CONCLUSION: The comparable results observed across trials presents a welcome opportunity to reduce toxicity by eliminating excessive doses of chemotherapy (i.e. vincristine, cisplatin, and cyclophosphamide) from therapy. Furthermore, these results support molecularly driven risk classification as the means for a better, more-refined, treatment stratification.

[68Ga]Ga-PSMA-11 PET baseline imaging as a prognostic tool for clinical outcomes to [177Lu]Lu-PSMA-617 in patients with mCRPC: A VISION substudy

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Background: In the phase 3 VISION study, gallium (68Ga) gozetotide (68Ga-PSMA-11) PET/CT imaging was used to determine eligibility for lutetium (177Lu) vipivotide tetraxetan (177Lu-PSMA-617). Given that 177Lu-PSMA-617 targets PSMA, we assessed the association between quantitative PSMA imaging parameters and treatment outcomes. Methods: In VISION, adults with mCRPC with ≥ 1 PSMA-positive (+) and no PSMA-negative lesions meeting the exclusion criteria were enrolled. In this sub-study, the association between imaging data from pre-enrollment 68Ga-PSMA-11 PET/CT scans of pts in the 177Lu-PSMA-617 group and clinical outcomes was assessed. Imaging data meeting quality requirements were analyzed for 548/551 pts. PSMA expression was quantified by 5 PET parameters: PSMA+ lesions by region, mean standardized uptake value (SUVmean), maximum SUV (SUVmax), PSMA+ tumor volume, and tumor load (PSMA+ tumor volume × SUVmean). Parameters were extracted from the whole body and 4 regions. Association between PET parameters and radiographic progression-free survival (rPFS; primary objective), overall survival (OS), objective response rate (ORR), and prostate–specific antigen 50 (PSA50) response was assessed. Results: Most pts (92.7%) had PSMA uptake in bone. In both the whole-body and regional analyses, statistically significant associations of PSMA PET parameters to clinical outcomes were observed (whole-body data shown in Table). Higher whole-body SUVmean was associated with improved clinical outcomes; pts in the highest quartile (SUVmean: rPFS, ≥ 10.2; OS, ≥ 9.9) had a median rPFS and OS of 14.1 and 21.4 months, vs 5.8 and 14.5 months for those in the lowest quartile (< 6.0; < 5.7), respectively. Absence of PSMA+ lesions in bone, liver, and lymph node, and lower PSMA+ tumor load, were indicators of good prognosis. Conclusions: Higher SUVmean is strongly associated with improved outcomes with 177Lu-PSMA-617; clinical efficacy for different SUV levels vs the SoC arm is being assessed. Data support use of 68Ga-PSMA-11 PET/CT scan to identify pts who will benefit from PSMA-targeted radioligand therapy.[Table: see text]

Survival Outcomes in Men with Unfavorable Intermediate-Risk and High-Risk Prostate Cancer Treated with Prostate-Only versus Whole Pelvic Radiation Therapy

PURPOSE

Men with unfavorable intermediate-risk (UIR-PCa) or high-risk prostate cancer (HR-PCa) are often treated with definitive external beam radiotherapy (EBRT) plus androgen deprivation therapy. Treatment is frequently intensified by electively treating the pelvic lymph nodes (LNs) with whole pelvis radiotherapy (WPRT), but practice patterns and the benefits of WPRT are not well defined. We hypothesized that men treated with WPRT would have improved overall survival (OS) relative to men treated with prostate-only radiotherapy.

MATERIALS AND METHODS

National Cancer Database records of men diagnosed between 2008-2015 with UIR-PCa or HR-PCa and treated with prostate EBRT±androgen deprivation therapy (72-86.4 Gy) with (15,175) or without (13,549) WPRT were reviewed. Risk of LN involvement was calculated using the Memorial Sloan Kettering Cancer Center nomogram. Measured confounders were balanced with inverse probability of treatment weighting and OS hazard ratios (HRs) were generated using multivariable Cox regression.

RESULTS

Of the men, 53% received WPRT. Every 1% increase in risk of LN involvement correlated with a 1% increase in risk of death (p <0.001). WPRT trended toward improved OS in all men with UIR-PCa and HR-PCa (HR: 0.95 [95% CI: 0.90-1.006], p=0.055). WPRT correlated with improved OS in men with Gleason 9 and 10 disease (HR: 0.87 [0.78-0.98], p=0.02) or risk of LN involvement ≥10% (HR: 0.93 [0.87-0.99], p=0.03).

CONCLUSIONS

Men with higher LN risk scores and Gleason grade benefited from WPRT. These results complement the recent POP-RT randomized trial in mostly positron emission tomography/computerized tomography-staged patients, demonstrating that a more heterogeneous population of men staged without functional imaging benefits from WPRT.

Methodological Comparison of Mapping the Expanded Prostate Cancer Index Composite to EuroQoL-5D-3L Using Cross-Sectional and Longitudinal Data: Secondary Analysis of NRG/RTOG 0415

PURPOSE

To compare the predictive ability of mapping algorithms derived using cross-sectional and longitudinal data.

METHODS

This methodological assessment used data from a randomized controlled noninferiority trial of patients with low-risk prostate cancer, conducted by NRG Oncology (ClinicalTrials.gov identifier: NCT00331773), which examined the efficacy of conventional schedule versus hypofractionated radiation therapy (three-dimensional conformal external beam radiation therapy/IMRT). Health-related quality-of-life data were collected using the Expanded Prostate Cancer Index Composite (EPIC), and health utilities were obtained using EuroQOL-5D-3L (EQ-5D) at baseline and 6, 12, 24, and 60 months postintervention. Mapping algorithms were estimated using ordinary least squares regression models through five-fold cross-validation in baseline cross-sectional data and combined longitudinal data from all assessment periods; random effects specifications were also estimated in longitudinal data. Predictive performance was compared using root mean square error. Longitudinal predictive ability of models obtained using baseline data was examined using mean absolute differences in the reported and predicted utilities.

RESULTS

A total of 267 (and 199) patients in the estimation sample had complete EQ-5D and EPIC domain (and subdomain) data at baseline and at all subsequent assessments. Ordinary least squares models using combined data showed better predictive ability (lowest root mean square error) in the validation phase for algorithms with EPIC domain/subdomain data alone, whereas models using baseline data outperformed other specifications in the validation phase when patient covariates were also modeled. The mean absolute differences were lower for models using EPIC subdomain data compared with EPIC domain data and generally decreased as the time of assessment increased.

CONCLUSION

Overall, mapping algorithms obtained using baseline cross-sectional data showed the best predictive performance. Furthermore, these models demonstrated satisfactory longitudinal predictive ability.

The addition of androgen deprivation therapy and pelvic lymph node treatment to prostate bed salvage radiotherapy (NRG Oncology/RTOG 0534 SPPORT): an international, multicentre, randomised phase 3 trial

BACKGROUND

In men with a detectable prostate-specific antigen (PSA) level after prostatectomy for prostate cancer, salvage prostate bed radiotherapy (PBRT) results in about 70% of patients being free of progression at 5 years. A three-group randomised trial was designed to determine whether incremental gains in patient outcomes can be achieved by adding either 4-6 months of short-term androgen deprivation therapy (ADT) to PBRT, or both short-term ADT and pelvic lymph node radiotherapy (PLNRT) to PBRT.

METHODS

The international, multicentre, randomised, controlled SPPORT trial was done at 283 radiation oncology cancer treatment centres in the USA, Canada, and Israel. Eligible patients (aged ≥18 years) were those who after prostatectomy for adenocarcinoma of the prostate had a persistently detectable or an initially undetectable and rising PSA of between 0·1 and 2·0 ng/mL. Patients with and without lymphadenectomy (N0/Nx) were eligible if there was no clinical or pathological evidence of lymph node involvement. Other eligibility criteria included pT2 or pT3 disease, prostatectomy Gleason score of 9 or less, and a Zubrod performance status of 0-1. Eligible patients were randomly assigned to receive PBRT alone at a dose of 64·8-70·2 Gy at 1·8 Gy per fraction daily (group 1), PBRT plus short-term ADT (group 2), or PLNRT (45 Gy at 1·8 Gy per fraction, and then a volume reduction made to the planning target volume for the remaining 19·8-25 ·2 Gy) plus PBRT plus short-term ADT (group 3). The primary endpoint was freedom from progression, in which progression was defined as biochemical failure according to the Phoenix definition (PSA ≥2 ng/mL over the nadir PSA), clinical failure (local, regional, or distant), or death from any cause. A planned interim analysis of 1191 patents with minimum potential follow-up time of 5 years applied a Haybittle-Peto boundary of p<0·001 (one sided) for comparison of 5-year freedom from progression rates between the treatment groups. This trial is registered with ClinicalTrials.gov, NCT00567580. The primary objectives of the trial have been completed, although long-term follow-up is continuing.

FINDINGS

Between March 31, 2008, and March 30, 2015, 1792 eligible patients were enrolled and randomly assigned to the three treatment groups (592 to group 1 [PBRT alone], 602 to group 2 [PBRT plus short-term ADT], and 598 to group 3 [PLNRT plus PBRT plus short-term ADT]). 76 patients subsequently found to be ineligible were excluded from the analyses; thus, the evaluable patient population comprised 1716 patients. At the interim analysis (n=1191 patients; data cutoff May 23, 2018), the Haybittle-Peto boundary for 5-year freedom from progression was exceeded when group 1 was compared with group 3 (difference 17·9%, SE 2·9%; p<0·0001). The difference between groups 2 and 3 did not exceed the boundary (p=0·0063). With additional follow-up beyond the interim analysis (the final planned analysis; data cutoff May 26, 2021), at a median follow-up among survivors of 8·2 years (IQR 6·6-9·4), the 5-year freedom from progression rates in all 1716 eligible patients were 70·9% (95% CI 67·0-74·9) in group 1, 81·3% (78·0-84·6) in group 2, and 87·4% (84·7-90·2) in group 3. Per protocol criteria, freedom from progression in group 3 was superior to groups 1 and 2. Acute (≤3 months after radiotherapy) grade 2 or worse adverse events were significantly more common in group 3 (246 [44%] of 563 patients) than in group 2 (201 [36%] of 563; p=0·0034), which, in turn, were more common than in group 1 (98 [18%] of 547; p<0·0001). Similar findings were observed for grade 3 or worse adverse events. However, late toxicity (>3 months after radiotherapy) did not differ significantly between the groups, apart from more late grade 2 or worse blood or bone marrow events in group 3 versus group 2 (one-sided p=0·0060) attributable to the addition of PLNRT in this group.

INTERPRETATION

The results of this randomised trial establish the benefit of adding short-term ADT to PBRT to prevent progression in prostate cancer. To our knowledge, these are the first such findings to show that extending salvage radiotherapy to treat the pelvic lymph nodes when combined with short-term ADT results in meaningful reductions in progression after prostatectomy in patients with prostate cancer.

FUNDING

National Cancer Institute.

Considerations on Integrating Prostate-Specific Membrane Antigen Positron Emission Tomography Imaging Into Clinical Prostate Cancer Trials by National Clinical Trials Network Cooperative Groups

PURPOSE

As prostate-specific membrane antigen (PSMA) positron emission tomography (PET) becomes increasingly available in the United States, the greater sensitivity of the technology in comparison to conventional imaging poses challenges for clinical trials. The NCI Clinical Imaging Steering Committee (CISC) PSMA PET Working Group was convened to coordinate the identification of these challenges in various clinical scenarios and to develop consensus recommendations on how best to integrate PSMA PET into ongoing and upcoming National Clinical Trials Network (NCTN) trials.

METHODS

NCI CISC and NCI Genitourinary Steering Committee members and leadership nominated clinicians, biostatisticians, patient advocates, and other imaging experts for inclusion in the PSMA PET Working Group. From April to July 2021, the working group met independently and in conjunction with the CISC to frame challenges, including stage migration, response assessment, trial logistics, and statistical challenges, and to discuss proposed solutions. An anonymous, open-ended survey was distributed to members to collect feedback on challenges faced. Representatives from each NCTN group were invited to present an overview of affected trials. From these discussions, the consensus document was developed and circulated for the inclusion of multiple rounds of feedback from both the Working Group and CISC.

RESULTS

The current consensus document outlines the key challenges for clinical prostate cancer trials resulting from the increasing availability of PSMA PET. We discuss implications for patient selection and definition of end points and provide guidance and potential solutions for different clinical scenarios, particularly with regard to best practices in defining eligibility criteria and outcome measures.

RECOMMENDATIONS

This article provides guidance regarding clinical trial design and conduct, and the interpretation of trial results.

Propensity-Weighted Survival Analysis of SBRT vs. Conventional Radiotherapy in Unfavorable Intermediate-Risk Prostate Cancer

BACKGROUND

Prostate stereotactic body radiotherapy (SBRT), which delivers high-dose precision treatment in ≤5 fractions, is a shorter, more convenient, and less expensive alternative to conventionally fractionated radiotherapy (CRFT; ∼44 fractions) or moderately hypofractionated radiotherapy (MFRT; 20-28 fractions). SBRT has not been widely adopted but may have radiobiologic advantages over CFRT/MFRT. We hypothesized that SBRT would be associated with improved overall survival (OS) versus CFRT or MFRT ± androgen deprivation therapy (ADT) for unfavorable-intermediate-risk prostate cancer (UIR-PCa).

METHODS

Men with UIR-PCa treated with SBRT (35-40Gy in ≤5 fractions) or biologically equivalent doses of CFRT (72-86.4Gy in 1.8-2.0Gy/fraction) or MRFT (≥60Gy in 2.4-3.2Gy/fraction; biologically effective doses ≥120) were identified in the National Cancer Database (NCDB). Unweighted and propensity-weighted multivariable Cox analysis (MVA) was used to compare OS hazard ratios.

RESULTS

Of 28,028 men with UIR-PCa who received CFRT with (n = 12,872) or without ADT (n = 12,984); MFRT with (n = 251) or without ADT (n = 281); and SBRT with (n = 212) or without ADT (n = 1,428) were identified. Relative to CFRT without ADT, CFRT+ ADT (HR 0.92, 95% CI 0.87-0.97, P = .002) and SBRT without ADT (HR 0.74, 95% CI 0.61-0.89, P = .002) were both associated with improved OS on MVA. Relative to CFRT+ADT, SBRT without ADT correlated with improved OS on MVA (HR:0.81, 95% CI 0.67-0.99, P = .04). Propensity-weighted MVA demonstrated that SBRT (HR:0.80, 95% CI 0.65-0.98, P = .036) and ADT (HR:0.91, 95% CI 0.86-0.97, P = .002) correlated with improved OS. SBRT was not associated with improved OS versus MFRT.

CONCLUSION

SBRT, which offers a cheaper and shorter treatment course that mitigates COVID-19 exposure, was associated with improved OS versus CFRT for UIR-PCa. These results confirm guideline-based recommendations that SBRT is a viable option for UIR prostate cancer. The results from this large retrospective study require further validation in clinical trials.

Treatment Patterns and Overall Survival Outcomes Among Patients Aged 80 yr or Older with High-risk Prostate Cancer

BACKGROUND

Elderly patients diagnosed with high-risk prostate cancer (PCa) present a therapeutic dilemma of balancing treatment of a potentially lethal malignancy with overtreatment of a cancer that may not threaten life expectancy.

OBJECTIVE

To investigate treatment patterns and overall survival outcomes in this group of patients.

DESIGN SETTING AND PARTICIPANTS

A retrospective cohort study was conducted. We queried the National Cancer Database for high-risk PCa in patients aged 80 yr or older diagnosed during 2004-2016.

INTERVENTION

Eligible patients underwent no treatment following biopsy (ie, observation), androgen deprivation therapy (ADT) alone, radiation therapy (RT) alone, RT + ADT, or surgery.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Kaplan-Meier, log rank, and multivariate Cox proportional hazard regression was performed to compare overall survival (OS).

RESULTS AND LIMITATIONS

A total of 19 920 men were eligible for analysis, and the most common treatment approach was RT + ADT (7401 patients; 37.2%). Observation and ADT alone declined over time (59.3% in 2004 vs 47.5% in 2016). There was no observed difference in OS between observation and ADT alone (adjusted hazard ratio [HR] 1.04, 95% confidence interval [CI], 0.99-1.09; p = 0.105). Definitive local treatment was associated with improved OS compared with ADT alone (RT alone, HR 0.54, 95% CI, 0.50-0.59, p < 0.0001; ADT + RT, HR 0.48, 95% CI, 0.46-0.50, p < 0.0001; surgery, HR 0.50, 95% CI, 0.42-0.59, p < 0.0001).

CONCLUSIONS

This analysis demonstrates that the use of definitive local therapy, including surgery or RT ± ADT, is increasing and is associated with a 50% reduction in overall mortality compared with observation or ADT alone. While prospective validation is warranted, elderly men with high-risk disease eligible for definitive management should be counseled on the risks, including a possible compromise in OS, with deferring definitive management.

PATIENT SUMMARY

Elderly men are more often diagnosed with higher-risk prostate cancer but are less likely to receive curative treatment options than younger men. Our analysis demonstrates that for men ≥80 yr of age with high-risk prostate cancer, definitive local therapy, including surgery or radiation therapy and/or androgen deprivation therapy, is associated with a 50% reduction in overall mortality compared with observation or androgen deprivation therapy alone. We therefore recommend that life expectancy (ie, physiologic age) be taken into account, over chronologic age, and that elderly men with good life expectancy (eg, >5 yr; minimal comorbidity) should be offered definitive, life-prolonging therapy.

Outcomes of Patients With Unfavorable Intermediate-Risk Prostate Cancer Treated With External-Beam Radiotherapy Versus Brachytherapy Alone

BACKGROUND

The NCCN Guidelines for Prostate Cancer currently recommend several definitive radiotherapy (RT) options for men with unfavorable intermediate-risk (UIR) prostate cancer: external-beam RT (EBRT) plus androgen deprivation therapy (ADT) or EBRT plus brachytherapy boost with or without ADT. However, brachytherapy alone with or without ADT is not well defined and is currently not recommended for UIR prostate cancer. We hypothesized that men treated with brachytherapy with or without ADT have comparable survival rates to men treated with EBRT with or without ADT.

METHODS

A total of 31,783 men diagnosed between 2004 and 2015 with UIR prostate cancer were retrospectively reviewed from the National Cancer Database. Men were stratified into 4 groups: EBRT (n=12,985), EBRT plus ADT (n=12,960), brachytherapy (n=4,535), or brachytherapy plus ADT (n=1,303). Inverse probability of treatment weighting (IPTW) was used to adjust for covariable imbalances, and weight-adjusted multivariable analysis (MVA) using Cox regression modeling was used to compare overall survival (OS) hazard ratios (HRs).

RESULTS

Relative to EBRT alone, the following treatments were associated with improved OS: EBRT plus ADT (HR, 0.92; 95% CI, 0.87-0.97; P=.002), brachytherapy alone (HR, 0.90; 95% CI, 0.83-0.98; P=.01), and brachytherapy plus ADT (HR, 0.78; 95% CI, 0.69-0.88; P=.00006). Brachytherapy correlated with improved OS relative to EBRT in men who were not treated with ADT (HR, 0.92; 95% CI, 0.84-0.99; P=.03) and in those receiving ADT (HR, 0.84; 95% CI, 0.75-0.95; P=.004). At 10-year follow-up, 56% and 63% of men receiving EBRT and brachytherapy, respectively, were alive (P<.0001). IPTW was used to determine the average treatment effect of definitive brachytherapy. Relative to EBRT, definitive brachytherapy correlated with improved OS (HR, 0.90; 95% CI, 0.84-0.97; P=.009) on weight-adjusted MVA.

CONCLUSIONS

Definitive brachytherapy was associated with improved OS compared with EBRT. The addition of ADT to both EBRT and definitive brachytherapy was associated with improved OS. These results suggest that definitive brachytherapy should be considered as an option for men with UIR prostate cancer.

External beam radiation therapy with or without brachytherapy boost for low PSA, high-grade prostate cancer

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Background: Radiation dose escalation with the addition of a brachytherapy boost (BT) to external beam radiation therapy (EBRT) may be associated with improved survival in certain men with Gleason grade 5 (GG5) prostate cancer (PCa). However, low PSA, high-grade PCa has much worse outcomes, is associated with neuroendocrine genomic features, and may be more resistant to androgen suppression. It is unclear whether the addition of a BT boost in men with this disease subgroup is associated with a survival benefit and is the subject of this analysis. Methods: Men diagnosed with node-negative, non-metastatic GG5 PCa and treated with (1) EBRT plus ADT or (2) EBRT plus BT plus ADT between 2004 and 2015 were identified in the National Cancer Database (NCDB). The EBRT cohort received conventionally fractionated ≥ 74 Gy or moderately hypofractionated (2.5-3.0 Gy x 20-28 fractions) EBRT. EBRT plus BT cohort received external beam doses of conventionally fractionated ≥45 Gy or moderately hypofractionated (2.5 Gy x 15 – 18 fractions) radiation, and either LDR or HDR BT. Men receiving chemotherapy, immunotherapy, or any form of surgery were excluded. Patients were stratified into two groups based on whether the presenting PSA was above or below the normal threshold (≤4 and > 4 ng/mL). OS was compared using the Kaplan-Meier and log-rank test. Multivariable analysis (MVA) using Cox proportional hazards regression modeling was performed, accounting for age, race, year of diagnosis, Charlson-Deyo comorbidity score, insurance status, treatment facility type, Gleason Score (9 versus 10), and clinical T-stage. Results: 8,260 men met study inclusion criteria of which 658 (8%) presented with PSA ≤4. 572 (87%) patients were treated with EBRT monotherapy and 86 (13%) patients were treated with EBRT + BT. 5-year OS for EBRT versus EBRT plus BT was 79.7 +/- 2.3% versus 86.9 +/- 5.0%, respectively (P = 0.49). On MVA analysis, EBRT plus BT was not associated with improved OS versus EBRT (adjusted HR 0.90, 95% CI 0.52-1.87; P = 0.62). In comparison, for men with PSA > 4 and GG5 disease [EBRT: 6,780 patients (89.2%) & EBRT plus BT: 822 patients (10.8%)], EBRT plus BT was associated with improved OS versus EBRT (adjusted HR 0.85, 95% CI 0.66-0.99; P = 0.044). Conclusions: Receipt of dose-escalated prostate radiation by means of a BT boost was not associated with improved survival in men with PSA ≤4 ng/mL and GG5 prostate cancer. By contrast, an association with improved survival was observed in men with GG5 disease and higher initial PSA. This low PSA, high-grade subgroup may represent a unique risk tier for which current treatment paradigms need further investigation, including study of escalated systemic therapy.

Validation of the performance of the Decipher biopsy genomic classifier in intermediate-risk prostate cancer on the phase III randomized trial NRG Oncology/RTOG 0126

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Background: The 22-gene Decipher genomic classifier (GC) is a prognostic biomarker that has been validated in phase III trials in high-risk localized, post-prostatectomy, and metastatic and non-metastatic castration-resistant prostate cancer. Herein, we report the first validation of the biopsy GC in intermediate-risk prostate cancer from the phase III randomized trial NRG/RTOG 0126. Methods: After National Cancer Institute approval, biopsy slides were collected from the NRG biobank from RTOG 0126, a phase III randomized trial of men with intermediate-risk prostate cancer randomized to 70.2 Gy versus 79.2 Gy of radiotherapy without the use of concomitant hormone therapy. RNA was extracted from the highest grade tumor foci and processed through a quality control (QC) pipeline prior to generation of the previously locked 22-gene GC model. After GC data was generated it was linked with clinical outcomes to assess prognostic performance. The primary endpoint for this ancillary project was disease progression, defined as biochemical failure, local failure, distant metastasis or prostate cancer-specific mortality, as well as use of salvage therapy. Secondary endpoints included the previous individual endpoints, metastasis-free survival, and overall survival. Independent GC prognostic performance was assessed using cause-specific Cox or competing risk adjusted Fine-Gray multivariable models that included randomization arm and prognostic stratification factors. Death without events were treated as competing risks. Results: A total of 215 patient samples passed QC of the 449 that had suitable cDNA for expression analysis. The median follow-up was 12.8 years (range 2.4-17.7), and 61% had Gleason 3+4, 24% had Gleason 4+3, and the median PSA was 7.2 ng/mL (IQR 5.0-10.2). On multivariable analysis the 22-gene GC (per 0.1 unit) was independently prognostic for disease progression (subdistribution hazard ratio [sHR] 1.13, 95%CI (1.01-1.26), p = 0.03), biochemical failure (sHR 1.23, 95%CI 1.10-1.37, p < 0.001), distant metastasis (sHR 1.28, 95%CI 1.06-1.54, p = 0.01), and PCSM (sHR 1.45, 95%CI 1.20-1.76, p < 0.001). In patients with lower GC scores the 10-year distant metastasis rate difference between the 70.2 Gy and 79.2 Gy was 5%, as compared with 26% for higher GC patients. Conclusions: This study represents the first validation of any biopsy-based gene expression classifier in intermediate-risk prostate cancer. Decipher is independently prognostic and can identify patients that have low rates of metastatic events despite not receiving concurrent hormone therapy, and can be used to help personalize therapy in this setting. Clinical trial information: NCT00033631.