Intratumoral androgen biosynthesis associated with 3β-hydroxysteroid dehydrogenase 1 promotes resistance to radiotherapy in prostate cancer

Half of all men with advanced prostate cancer (PCa) inherit at least 1 copy of an adrenal-permissive HSD3B1 (1245C) allele, which increases levels of 3β-hydroxysteroid dehydrogenase 1 (3βHSD1) and promotes intracellular androgen biosynthesis. Germline inheritance of the adrenally permissive allele confers worse outcomes in men with advanced PCa. We investigated whether HSD3B1 (1245C) drives resistance to combined androgen deprivation and radiotherapy. Adrenally permissive 3βHSD1 enhanced resistance to radiotherapy in PCa cell lines and xenograft models engineered to mimic the human adrenal/gonadal axis during androgen deprivation. The allele-specific effects on radiosensitivity were dependent on availability of DHEA, the substrate for 3βHSD1. In lines expressing the HSD3B1 (1245C) allele, enhanced expression of DNA damage response (DDR) genes and more rapid DNA double-strand break (DSB) resolution were observed. A correlation between androgen receptor (AR) expression and increased DDR gene expression was confirmed in 680 radical prostatectomy specimens. Treatment with the nonsteroidal antiandrogen enzalutamide reversed the resistant phenotype of HSD3B1 (1245C) PCa in vitro and in vivo. In conclusion, 3βHSD1 promotes prostate cancer resistance to combined androgen deprivation and radiotherapy by upregulating DNA DSB repair. This work supports prospective validation of early combined androgen blockade for high-risk men harboring the HSD3B1 (1245C) allele.

Patterns of Recurrence Following Radiation and ADT for Pathologic Lymph Node Positive Prostate Cancer: A Multi-Institutional Study

PURPOSE/OBJECTIVE(S)

Retrospective studies have suggested that post-operative radiation therapy (RT) can reduce the risk of cause-specific mortality in men with pathologic nodal involvement (pN1) after radical prostatectomy (RP). We evaluated prognostic factors and patterns of recurrence in patients who received post-operative RT +/- androgen deprivation therapy (ADT) for pN1 disease in a multicentric cohort of 4 academic centers.

MATERIALS/METHODS

Data from patients with pN1 prostate cancer after RP who subsequently received RT with short term (< = 6 mo) or long term (>6 mo) ADT were obtained from 4 academic institutions. Patterns of recurrence, biochemical progression free survival (bPFS) and distant metastasis free survival (DMFS) were evaluated.

RESULTS

A total of 270 patients with a median follow-up of 48 months were included. Gleason grade group (GG) 2 was present in 20 patients (7.5%), GG 3 in 81 (30%), GG4 in 36 (13.5%), GG5 in 130 (49%) patients. 256 (95%) patients had extracapsular extension, 70% had seminal vesicle invasion, 59% had positive surgical margins, and 66% had a detectable post-operative PSA. The number of positive nodes at surgery were 1 in 59%, 2 in 19% and >2 in 22% of patients. Of the 83 patients that had pre-RT imaging, 46 (55%) had a PET scan (PSMA, or fluciclovine); 25 (30%) of those had lymph nodes detected on imaging prior to RT. Median time from RP to RT was 6 mo (IQR 4.5-9.1 mo). 96% received radiation to both the prostate bed (median dose 68.4Gy) and pelvic lymph nodes (median dose 46Gy). ADT was prescribed short-term (20%) or long-term (68%), while 26 (10%) received no ADT, and 7 (3%) had an unknown duration. Biochemical failure (bF) was observed in 29% of men, with 5% having pelvic nodal failure and 11.5% having distant metastases (majority in bones, followed by paraaortic nodes) at last follow up. Of 59 patients who had normal baseline testosterone levels, 37% recovered their testosterone by last follow-up. The 4-year bRFS was 72% for all patients and was 83% for those with a pre-RT PSA of <0.1 ng/mL, 76% for PSA 0.1-<0.5 ng/mL, 60% for PSA 0.5-2 ng/mL, and 35% for PSA >2 ng/mL. On multivariable analysis, maximum pre-RT PSA ≥0.5 (0.5 to 2.0 vs <0.1 HR = 3.19; >2.0 vs <0.1 HR = 9.00), use of LTADT (HR = 0.47), and percent pN1 (HR = 1.03) were significantly associated with bF. Pre-RT PSA >2 (HR = 4.10), use of LT ADT (HR = 0.33) and percent pN1 (HR = 1.03) were also significantly associated with DM.

CONCLUSION

In pN1 patients, pelvic RT and ADT at low PSA levels is associated with improved oncologic outcomes compared to treatment at higher levels, suggesting that PSA may have prognostic value for pN1 prostate cancer.

Outcomes with Five Fraction Image-Guided Partial Breast Irradiation to Reduced Target Volumes

PURPOSE/OBJECTIVE(S)

The use of 5-fraction partial breast irradiation has been shown in a randomized trial to provide comparable rates of local control and reduced toxicities as compared to standard fractionation whole breast irradiation. The initial technique utilized a 2 cm expansion on the lumpectomy cavity (1 cm for clinical target volume [CTV], and 1 cm planning target volume [PTV]) without consistent image guidance (ex. cone beam computed tomography [CBCT]) or motion management recommendations. We present clinical outcomes using a 5-fraction image guided PBI technique (IG-PBI) to reduced target volumes for patients with early-stage breast cancer.

MATERIALS/METHODS

A retrospective review of an IRB approved institutional registry was performed to identify patients treated with IG-PBI. A total of 258 patients with early-stage breast cancer (Stage 0-IIA) receiving IG-PBI were identified. Patients received a dose of 30 Gy in 5 fractions delivered daily or every other day. An expansion of 1 cm on the lumpectomy cavity was used for those patients using deep inspiration breath hold (DIBH) while an expansion of 1.5 cm was utilized for those not using DIBH. All patients received daily CBCT. Plans were delivered using intensity-modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT) technique; while the prescription isodose line covered the PTV, the 26 Gy line was allowed to expand beyond the PTV. Kaplan-Meier analyses were used to assess rates of local control and survival. Patient demographics, stage, hormone therapy use, recurrence, mortality, and toxicity data were collected. Survival was analyzed with Kaplan-Meier curve.

RESULTS

Median age at diagnosis was 67 years (range 40-87) with a median follow-up of 29 months (IQR 22-40). Forty-six (18%) patients had in situ disease, 200 (78%) patients T1 tumors, and 12 (5%) patients had T2 tumors. Two hundred thirty-four (91%) patients were White, 15 (6%) were Black, and 9 (4%) were other races. One hundred ninety-six (76%) patients received endocrine therapy, and 16 (6%) patients received chemotherapy. Thirty-two (12%) patients developed grade 1 dermatitis and no grade 2 events were observed. One (0.4%) patient had a cardiac event (aortic stenosis) 19 months after breast radiotherapy. At last follow-up, one (0.4%) patient had a local recurrence and one (0.4%) developed a distant metastasis, with no regional nodal failures. Overall, 4 (1.5%) patients had died, all due to other causes. At 3 years, locoregional control was 99.4%.

CONCLUSION

Outcomes with IG-PBI demonstrate low rates of local recurrence and limited toxicity. The use of reduced target volumes is not associated with increased rates of local recurrence.

Five Fraction Accelerated Partial Breast Irradiation vs. Intraoperative Radiation Therapy for Early-Stage Breast Cancer

PURPOSE/OBJECTIVE(S)

Accelerated partial breast irradiation (APBI) represents an alternative to whole breast irradiation (WBI), reducing the target volume and potentially treatment duration. APBI delivered in 5 fractions with intensity modulated radiation therapy (IMRT) has been shown to have comparable outcomes to WBI with reduced toxicity profiles. In contrast, intraoperative radiation therapy (IORT) offers patients the potential to complete adjuvant radiation therapy in a single treatment. While early data were initially promising, concerns regarding long-term rates of local recurrence exist. We present a comparison of 5 fraction APBI versus IORT.

MATERIALS/METHODS

We performed a retrospective review of 473 patients with early-stage breast cancer (Stage 0-IIA) treated at a single institution with 258 receiving APBI and 215 IORT from October 2011 to May 2021. APBI patients received 30 Gy in 5 fractions delivered with IMRT daily or every other day. IORT patients received 20 Gy in 1 fraction prescribed to the applicator surface delivered at the time of surgery. Kaplan-Meier analysis was used to estimate locoregional control rates and overall survival among the 2 groups.

RESULTS

Mean age was 70.7 years old (IQR:67-74) for the IORT patients and 66.6 years old (IQR:62-72) for the APBI patients (p<0.001). Median follow up was 5.7 years for IORT patients and 2.4 years for APBI patients (p<0.001). For IORT patients, 11%/83.5%/5.5% of patients and for APBI 17.8%/77.5%/4.7% of patients had Tis/T1/T2 disease (p = 0.005). With regards to adjuvant therapies, 79%/76% of IORT/APBI patients were offered endocrine therapy (p = 0.50) and 1.4%/6.2% chemotherapy (p = 0.008). Recurrence at any time was seen in 7.9% (n = 17) of patients receiving IORT as compared to 0.8% (n = 2) of patients receiving APBI. APBI was however no differences in recurrence free survival (92.6% vs. 98.5%, p = .079) or overall survival were noted (92.8% vs. 95.1%, p = 0.99).

CONCLUSION

In a series of almost 500 patients with stage 0-IIA breast cancer, IORT was associated with higher rates of locoregional recurrence compared to APBI with no survival difference at 5 years. These outcomes, consistent with other series and current guidelines, suggest a limited role for IORT as monotherapy following breast conserving surgery.

Trial in Progress: Adaptive RADiation Therapy with Concurrent Sacituzumab Govitecan (SG) for Bladder Preservation in Patients with MIBC (RAD-SG)

PURPOSE/OBJECTIVE(S)

A substantial proportion of patients with muscle invasive bladder cancer do not receive curative intent therapy, especially if unfit for or refuse radical cystectomy. Concurrent chemoradiation is an effective alternative to radical cystectomy, however systemic radio-sensitizing chemotherapy may have off target side effects. A Phase I study is accruing which will investigate the concurrent administration of a bladder cancer targeted antibody drug conjugate (Sacituzumab Govitecan) with radiotherapy.

MATERIALS/METHODS

This trial in progress is a Phase I study of Adaptive RADiation therapy with concurrent Sacituzumab Govitecan (SG) for bladder preservation in patients with muscle invasive bladder cancer (MIBC). Eligible patients will have localized muscle invasive bladder cancer (MIBC) confined to the bladder. The initial cohort is expected to accrue 20 patients. The primary endpoint is to establish the safety, tolerability, and feasibility of bladder preservation therapy treatment with concurrent SG and adaptive image-guided radiation therapy for patients with localized MIBC. The secondary endpoints are to determine the bladder intact event-free survival (BI-EFS) with concurrent SG and radiation therapy for MIBC and compare to historical controls with other concurrent chemoradiation regimens. BI-EFS is defined as the time from treatment to the first documented occurrence of residual/recurrent MIBC, nodal or distant metastases on imaging, radical cystectomy, or death from any cause. Sacituzumab Govitecan targets TROP-2, a surface protein expressed in urothelial cancers of the bladder. SG will be delivered IV, 10 mg/kg, 21-day cycles for 1 loading cycle prior to radiation and two subsequent cycles with concurrent adaptive radiotherapy over a period of 6 weeks (64 Gy). Correlative objectives (Supported by NCI/NIH U54) and will involve 1) elucidation of the genetic and microenvironmental mechanisms that drive efficacy and resistance to combined ADC plus radiation therapy and 2) characterization of tumor clonal dynamics, immune repertoire editing, and imaging changes following treatment with SG plus radiation.

RESULTS

To be determined.

CONCLUSION

To be determined.

External Beam Radiation Therapy With or Without Brachytherapy Boost in Men With Very-High-Risk Prostate Cancer: A Large Multicenter International Consortium Analysis

PURPOSE

Very-high-risk (VHR) prostate cancer (PC) is an aggressive subgroup with high risk of distant disease progression. Systemic treatment intensification with abiraterone or docetaxel reduces PC-specific mortality (PCSM) and distant metastasis (DM) in men receiving external beam radiation therapy (EBRT) with androgen deprivation therapy (ADT). Whether prostate-directed treatment intensification with the addition of brachytherapy (BT) boost to EBRT with ADT improves outcomes in this group is unclear.

METHODS AND MATERIALS

This cohort study from 16 centers across 4 countries included men with VHR PC treated with either dose-escalated EBRT with ≥24 months of ADT or EBRT + BT boost with ≥12 months of ADT. VHR was defined by National Comprehensive Cancer Network (NCCN) criteria (clinical T3b-4, primary Gleason pattern 5, or ≥2 NCCN high-risk features), and results were corroborated in a subgroup of men who met Systemic Therapy in Advancing or Metastatic Prostate Cancer: Evaluation of Drug Efficacy (STAMPEDE) trials inclusion criteria (≥2 of the following: clinical T3-4, Gleason 8-10, or PSA ≥40 ng/mL). PCSM and DM between EBRT and EBRT + BT were compared using inverse probability of treatment weight-adjusted Fine-Gray competing risk regression.

RESULTS

Among the entire cohort, 270 underwent EBRT and 101 EBRT + BT. After a median follow-up of 7.8 years, 6.7% and 5.9% of men died of PC and 16.3% and 9.9% had DM after EBRT and EBRT + BT, respectively. There was no significant difference in PCSM (sHR, 1.47 [95% CI, 0.57-3.75]; P = .42) or DM (sHR, 0.72, [95% CI, 0.30-1.71]; P = .45) between EBRT + BT and EBRT. Results were similar within the STAMPEDE-defined VHR subgroup (PCSM: sHR, 1.67 [95% CI, 0.48-5.81]; P = .42; DM: sHR, 0.56 [95% CI, 0.15-2.04]; P = .38).

CONCLUSIONS

In this VHR PC cohort, no difference in clinically meaningful outcomes was observed between EBRT alone with ≥24 months of ADT compared with EBRT + BT with ≥12 months of ADT. Comparative analyses in men treated with intensified systemic therapy are warranted.

Disparities in prostate cancer diagnoses in persons experiencing homelessness

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Background: We previously reported that persons experiencing homelessness (PEH) are significantly less likely to undergo prostate specific antigen (PSA) testing compared to persons not experiencing homelessness (non-PEH). The purpose of this study was to determine if reduced PSA testing in PEH results in more advanced prostate cancer diagnoses. Methods: We identified PSA screening eligible PEH (men ages 50-69) from an institutional registry of all patients that presented to our healthcare system as homeless from 2014 to 2021. A matched cohort of non-PEH was generated for comparison. Institutional CPT and HCPCS billing codes for PSA testing were available beginning 01/01/2017 and cross-referenced to identify PEH and non-PEH who underwent PSA testing at least once between 01/01/2017 and 12/31/2021. In patients with ≥ 1 PSA test, we recorded screening, oncologic and treatment related variables. Patients with a history of prostate cancer diagnosed outside the study timeframe were excluded. Results: A total of 9,249 PEH were identified, with 1,597 meeting PSA screening criteria during the study timeframe; 3,370 screening eligible non-PEH were available for comparison. The median age was 59.0 for PEH and 60.0 for non-PEH. PEH were significantly less likely to have a primary care provider (58% vs 81%, p<0.001) or to have a PSA test (12% vs 33%, p<0.001). Among patients with a PSA test, PEH were significantly less likely to have multiple PSA tests compared to non-PEH (28% vs 61%, p<0.001) and significantly more likely to have a PSA ≥ 4.0 (18% vs 12%, p=0.028). In patients with a PSA ≥ 4.0, PEH were less likely to receive a prostate biopsy (37% vs 61%, p =0.009) and there was a trend towards decreased prostate MRI (11% vs 25%, p=0.085). A total of 6 PEH (0.4%) and 46 non-PEH (1.4%) were diagnosed with prostate cancer. The median PSA at diagnosis was 12.6 in PEH vs 7.0 in non-PEH (p=0.052). PEH were significantly more likely to present with high/very high risk disease (4/6 [66%] vs 9/46 [20%], p=0.019); no PEH had very low/low risk disease compared with 20 (43.5%) non-PEH. PEH were more likely to present with lymph node positive or metastatic disease (3/6 [50%] vs 3/46 [7%], p=0.016). The median time from biopsy to treatment was 119 days in PEH and 76 days in non-PEH (p=0.391). Conclusions: PEH are less likely to receive prostate cancer testing following an elevated PSA and more likely to present with high risk advanced prostate cancer. Interventions to increase prostate cancer awareness in PEH are needed to reduce disparities.

Prostate Cancer Screening Disparities in Persons Experiencing Homelessness

PURPOSE

The purpose of this study was to assess prostate-specific antigen (PSA) testing rates in persons experiencing homelessness (PEH), identify factors associated with screening, and compare PSA screening rates in PEH with a matched cohort of persons not experiencing homelessness (non-PEH).

MATERIALS AND METHODS

We identified 9,249 potentially eligible PEH cared for at a large metropolitan hospital system from an institutional registry of all patients who presented to the health care system as homeless from 2014 to 2021. Homelessness was defined by the presence of the Z-code for homelessness (Z59), the listed address matching to the address of a homeless shelter or other transitional housing or a positive screen for homelessness. A matched cohort of 10,000 non-PEH was generated for comparison. Univariate chi-square analysis and multivariate logistic regression were performed to evaluate variables associated with PSA testing.

RESULTS

A total of 1,605 PEH and 3,413 non-PEH were eligible for PSA screening within the study timeframe. Half of PEH were Black (50%). Medicaid was the most common insurance (51%), followed by Medicare (18%). PEH were less likely to have a PCP (58% v 81%, P < .001) and had a significantly lower PSA testing rate (13% v 34%, P < .001) compared with non-PEH. Univariate analysis revealed that PSA testing was more common in PEH who were employed (P < .001), had private insurance or Medicare (P < .001), or had an established primary care provider (PCP; P < .001). Multivariate analysis confirmed that having a PCP (OR, 2.54; 95% CI, 1.62 to 4.00; P < .001) significantly increased the likelihood of PSA testing in PEH.

CONCLUSION

PEH experience low rates of prostate cancer screening. Interventions to increase screening in this population, including increased PCP access, are needed.

Cost effectiveness of treatment strategies for high risk prostate cancer

BACKGROUND

Patients with high-risk prostate cancer (HRPC) have multiple accepted treatment options. Because there is no overall survival benefit of one option over another, appropriate treatment must consider patient life expectancy, quality of life, and cost.

METHODS

The authors compared quality-adjusted life years (QALYs) and cost effectiveness among treatment options for HRPC using a Markov model with three treatment arms: (1) external-beam radiotherapy (EBRT) delivered with 20 fractions, (2) EBRT with 23 fractions followed by low-dose-rate (LDR) brachytherapy boost, or (3) radical prostatectomy alone. An exploratory analysis considered a simultaneous integrated boost according to the FLAME trial (ClinicalTrials.gov identifier NCT01168479).

RESULTS

Treatment strategies were compared using the incremental cost-effectiveness ratio (ICER). EBRT with LDR brachytherapy boost was a cost-effective strategy (ICER, $20,929 per QALY gained). These results were most sensitive to variations in the biochemical failure rate. However, the results still demonstrated cost effectiveness for the brachytherapy boost paradigm, regardless of any tested parameter ranges. Probabilistic sensitivity analysis demonstrated that EBRT with LDR brachytherapy was favored in 52% of 100,000 Monte Carlo iterations. In an exploratory analysis, EBRT with a simultaneous integrated boost was also a cost-effective strategy, resulting in an ICER of $62,607 per QALY gained; however, it was not cost effective compared with EBRT plus LDR brachytherapy boost.

CONCLUSIONS

EBRT with LDR brachytherapy boost may be a cost-effective treatment strategy compared with EBRT alone and radical prostatectomy for HRPC, demonstrating high-value care. The current analysis suggests that a reduction in biochemical failure alone can result in cost-effective care, despite no change in overall survival.

A multi-institutional prediction model to estimate the risk of recurrence and mortality after mastectomy for T1-2N1 breast cancer

Background

Post‐mastectomy radiation therapy (PMRT) in women with pathologic stage T1‐2N1M0 breast cancer is controversial.

Methods

Data from five North American institutions including women undergoing mastectomy without neoadjuvant therapy with pT1‐2N1M0 breast cancer treated from 2006 to 2015 were pooled for analysis. Competing‐risks regression was performed to identify factors associated with locoregional recurrence (LRR), distant metastasis (DM), overall recurrence (OR), and breast cancer mortality (BCM).

Results

A total of 3532 patients were included for analysis with a median follow‐up time among survivors of 6.8 years (interquartile range [IQR], 4.5–9.5 years). The 2154 (61%) patients who received PMRT had significantly more adverse risk factors than those patients not receiving PMRT: younger age, larger tumors, more positive lymph nodes, lymphovascular invasion, extracapsular extension, and positive margins (p < .05 for all). On competing risk regression analysis, receipt of PMRT was significantly associated with a decreased risk of LRR (hazard ratio [HR], 0.21; 95% confidence interval [CI], 0.14–0.31; p < .001) and OR (HR, 0.76; 95% CI, 0.62–0.94; p = .011). Model performance metrics for each end point showed good discrimination and calibration. An online prediction model to estimate predicted risks for each outcome based on individual patient and tumor characteristics was created from the model.

Conclusions

In a large multi‐institutional cohort of patients, PMRT for T1‐2N1 breast cancer was associated with a significant reduction in locoregional and overall recurrence after accounting for known prognostic factors. An online calculator was developed to aid in personalized decision‐making regarding PMRT in this population.

In a large multi‐institutional cohort of patients, post‐mastectomy radiation therapy (PMRT) for T1‐2N1 breast cancer was associated with a significant reduction in locoregional and overall recurrence after accounting for known prognostic factors. An online calculator was developed to aid in personalized decision‐making regarding PMRT in this population.

Breast cancer screening in persons experiencing homelessness

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Background: Persons experiencing homelessness (PEH) suffer from poor health outcomes, including worse cancer mortality, compared to persons not experiencing homelessness. A portion of the disparity in cancer outcomes is attributable to reduced access to cancer screening, leading to more advanced-stage disease and a higher risk of death compared to the general population. Data regarding cancer screening rates in PEH are scarce. We therefore sought to evaluate baseline rates of breast cancer screening in PEH. Methods: All patients presenting for care from January 1, 2014 onward at a hospital system spanning five counties in a populous Midwestern state were screened for homelessness. Homelessness was identified by two criteria: presence of the Z-code for homelessness (Z59) in the patient’s electronic medical record, and/or patient’s address on record listed as an address matching that of a regional homeless shelter, transitional housing, or “homeless.” Identified PEH were maintained in a prospective registry. For each female PEH in the screening age range, billing data for completed breast cancer screening mammography performed in the previous five years (1/1/17-12/31/21) were extracted (CPT codes 77063, 77067). Data were also extracted for a cohort of non-PEH patients eligible for screening. Demographic and clinical data were extracted for all patients. This study was approved by the hospital system’s IRB. Results: A total of 3,474 female (biological sex) PEH were identified, with 1,320 eligible for screening mammography (alive and between the ages of 40 and 79) in the study timeframe. The median age was 53.5 years old; 44% were Black, 48% White, 8.5% unknown/other race, and 3% Hispanic ethnicity. 28% of PEH were uninsured, and 67% had government insurance; 66% had an assigned primary care physician (PCP). Of PEH eligible for screening mammography, 237 (18%) had at least one screening mammogram during this five-year interval (2017, 2.2%; 2018, 4.3%; 2019, 3.6%; 2020, 3.7%; 2021, 4.3%). In a cohort of 6,240 non-PEH eligible for screening over the same timeframe, the screening mammography rate was 32%, which was significantly higher than the screening rate for PEH (p < 0.00001). Compared to PEH who did not undergo screening mammography, PEH who underwent screening mammography were more likely to have an assigned PCP (90% vs 38%, p < 0.00001), to be a non-current tobacco user (56% vs 35%, p < 0.00001), and to be a non-current illicit drug user (84 % vs 68%, p = 0.0015). PEH who underwent screening mammography were significantly less likely to be uninsured (12% vs 31%, p < 0.00001). Conclusions: In the largest study of its kind to date, we identified low rates of breast cancer screening in female PEH. Interventions to increase breast cancer screening in this vulnerable population are urgently needed and may include increased access to PCPs, tobacco and drug cessation programs, and provision of health insurance.

Interplay Between Duration of Androgen Deprivation Therapy and External Beam Radiotherapy With or Without a Brachytherapy Boost for Optimal Treatment of High-risk Prostate Cancer: A Patient-Level Data Analysis of 3 Cohorts

IMPORTANCE

Radiotherapy combined with androgen deprivation therapy (ADT) is a standard of care for high-risk prostate cancer. However, the interplay between radiotherapy dose and the required minimum duration of ADT is uncertain.

OBJECTIVE

To determine the specific ADT duration threshold that provides a distant metastasis-free survival (DMFS) benefit in patients with high-risk prostate cancer receiving external beam radiotherapy (EBRT) or EBRT with a brachytherapy boost (EBRT+BT).

DESIGN, SETTINGS, AND PARTICIPANTS

This was a cohort study of 3 cohorts assembled from a multicenter retrospective study (2000-2013); a post hoc analysis of the Randomized Androgen Deprivation and Radiotherapy 03/04 (RADAR; 2003-2007) randomized clinical trial (RCT); and a cross-trial comparison of the RADAR vs the Deprivación Androgénica y Radio Terapía (Androgen Deprivation and Radiation Therapy; DART) 01/05 RCT (2005-2010). In all, the study analyzed 1827 patients treated with EBRT and 1108 patients treated with EBRT+BT from the retrospective cohort; 181 treated with EBRT and 203 with EBRT+BT from RADAR; and 91 patients treated with EBRT from DART. The study was conducted from October 15, 2020, to July 1, 2021, and the data analyses, from January 5 to June 15, 2021.

EXPOSURES

High-dose EBRT or EBRT+BT for an ADT duration determined by patient-physician choice (retrospective) or by randomization (RCTs).

MAIN OUTCOMES AND MEASURES

The primary outcome was DMFS; secondary outcome was overall survival (OS). Natural cubic spline analysis identified minimum thresholds (months).

RESULTS

This cohort study of 3 studies totaling 3410 men (mean age [SD], 68 [62-74] years; race and ethnicity not collected) with high-risk prostate cancer found a significant interaction between the treatment type (EBRT vs EBRT+BT) and ADT duration (binned to <6, 6 to <18, and ≥18 months). Natural cubic spline analysis identified minimum duration thresholds of 26.3 months (95% CI, 25.4-36.0 months) for EBRT and 12 months (95% CI, 4.9-36.0 months) for EBRT+BT for optimal effect on DMFS. In RADAR, the prolongation of ADT for patients receiving only EBRT was not associated with significant improvements in DMFS (hazard ratio [HR], 1.01; 95% CI, 0.65-1.57); however, for patients receiving EBRT+BT, a longer duration was associated with improved DMFS (DMFS HR, 0.56; 95% CI, 0.36-0.87; P = .01). For patients receiving EBRT alone (DART), 28 months of ADT was associated with improved DMFS compared with 18 months (RADAR HR, 0.37; 95% CI, 0.17-0.80; P = .01).

CONCLUSIONS AND RELEVANCE

These cohort study findings suggest that the optimal minimum ADT duration for treatment with high-dose EBRT alone is more than 18 months; and for EBRT+BT, it is 18 months or possibly less. Additional studies are needed to determine more precise minimum durations.

A genomic classifier for prostate cancer correlates with adverse pathologic features: Transcriptomic features of cribriform and intraductal carcinoma of the prostate

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Background: Invasive cribriform and intraductal carcinoma (CF/IDC) portends an unfavorable prognosis for patients diagnosed with prostate cancer (CaP). Limited studies with small sample sizes have explored whether genomic classifiers are associated with IDC and/or CF status. We investigated the correlation between Decipher genomic risk score and IDC/CF status and assessed PCa transcriptomic features. Methods: We performed a retrospective review of CaP patients who had Decipher testing at a single high volume center between 2009-2020. The highest grade index lesion from radical prostatectomy specimens was identified by GU pathologists and used for Decipher testing. Genitourinary pathologists reviewed prostatectomy specimens for the presence of CF and IDC features. Patients were divided into three groups based on pathologic features, absent CF/IDC (CF-/IDC-), CF positive only (CF+/IDC-), and CF/IDC positive (CF+/IDC+). Categorical clinical, genomic, and pathologic variables were assessed using the Pearson Chi-Square test, quantitative with the Kruskal-Wallis test. Multivariable logistic regression was used to identify predictors of high-risk Decipher GC scores. The Kaplan-Meier method with log-rank was used to compare biochemical recurrence free survival. Differential gene expression and gene network analysis was used to identify genes and pathways associated with IDC/CF features. Results: 463 patients were included with a median follow-up of 25 months. Patients who were CF+/IDC+ had higher GC scores (CF+/IDC+: 0.77 vs. CF+/IDC-: 0.71 vs. CF-/IDC-: 0.61, p<0.001). Patients who were CF+/IDC+ had a higher percentage of Gleason grade group >3 (CF+/IDC+: 79% vs. CF+/IDC-: 52% vs. CF-/IDC-: 52%, p<0.001). On multivariate logistic regression, predictors of high-risk GC score were presence of CF+/IDC+ features on final pathology (OR: 3.94, p<0.001) and pathologic Gleason grade group >3 (OR: 1.58, p=0.04). Transcriptomic analysis revealed that the hallmark androgen response pathway was significantly upregulated in CF+/IDC+ patients (Log fold change: 15.7, p<0001). Conclusions: This is the largest series investigating the association of a clinically validated genomic classifier and pathologic features such as cribriform and intraductal carcinoma. These findings have implications for the use of genomic classifiers in settings where expert GU pathology is not readily available and in potentially unmasking adverse histology at the time of biopsy.[Table: see text]

Performance of a Prostate-Specific Membrane Antigen Positron Emission Tomography/Computed Tomography-Derived Risk-Stratification Tool for High-risk and Very High-risk Prostate Cancer

IMPORTANCE

Prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) can detect low-volume, nonlocalized (ie, regional or metastatic) prostate cancer that was occult on conventional imaging. However, the long-term clinical implications of PSMA PET/CT upstaging remain unclear.

OBJECTIVES

To evaluate the prognostic significance of a nomogram that models an individual's risk of nonlocalized upstaging on PSMA PET/CT and to compare its performance with existing risk-stratification tools.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study included patients diagnosed with high-risk or very high-risk prostate cancer (ie, prostate-specific antigen [PSA] level >20 ng/mL, Gleason score 8-10, and/or clinical stage T3-T4, without evidence of nodal or metastatic disease by conventional workup) from April 1995 to August 2018. This multinational study was conducted at 15 centers. Data were analyzed from December 2020 to March 2021.

EXPOSURES

Curative-intent radical prostatectomy (RP), external beam radiotherapy (EBRT), or EBRT plus brachytherapy (BT), with or without androgen deprivation therapy.

MAIN OUTCOMES AND MEASURES

PSMA upstage probability was calculated from a nomogram using the biopsy Gleason score, percentage positive systematic biopsy cores, clinical T category, and PSA level. Biochemical recurrence (BCR), distant metastasis (DM), prostate cancer-specific mortality (PCSM), and overall survival (OS) were analyzed using Fine-Gray and Cox regressions. Model performance was quantified with the concordance (C) index.

RESULTS

Of 5275 patients, the median (IQR) age was 66 (60-72) years; 2883 (55%) were treated with RP, 1669 (32%) with EBRT, and 723 (14%) with EBRT plus BT; median (IQR) PSA level was 10.5 (5.9-23.2) ng/mL; 3987 (76%) had Gleason grade 8 to 10 disease; and 750 (14%) had stage T3 to T4 disease. Median (IQR) follow-up was 5.1 (3.1-7.9) years; 1221 (23%) were followed up for at least 8 years. Overall, 1895 (36%) had BCR, 851 (16%) developed DM, and 242 (5%) died of prostate cancer. PSMA upstage probability was significantly prognostic of all clinical end points, with 8-year C indices of 0.63 (95% CI, 0.61-0.65) for BCR, 0.69 (95% CI, 0.66-0.71) for DM, 0.71 (95% CI, 0.67-0.75) for PCSM, and 0.60 (95% CI, 0.57-0.62) for PCSM (P < .001). The PSMA nomogram outperformed existing risk-stratification tools, except for similar performance to Staging Collaboration for Cancer of the Prostate (STAR-CAP) for PCSM (eg, DM: PSMA, 0.69 [95% CI, 0.66-0.71] vs STAR-CAP, 0.65 [95% CI, 0.62-0.68]; P < .001; Memorial Sloan Kettering Cancer Center nomogram, 0.57 [95% CI, 0.54-0.60]; P < .001; Cancer of the Prostate Risk Assessment groups, 0.53 [95% CI, 0.51-0.56]; P < .001). Results were validated in secondary cohorts from the Surveillance, Epidemiology, and End Results database and the National Cancer Database.

CONCLUSIONS AND RELEVANCE

These findings suggest that PSMA upstage probability is associated with long-term, clinically meaningful end points. Furthermore, PSMA upstaging had superior risk discrimination compared with existing tools. Formerly occult, PSMA PET/CT-detectable nonlocalized disease may be the main driver of outcomes in high-risk patients.

Comparison of Multimodal Therapies and Outcomes Among Patients With High-Risk Prostate Cancer With Adverse Clinicopathologic Features

IMPORTANCE

The optimal management strategy for high-risk prostate cancer and additional adverse clinicopathologic features remains unknown.

OBJECTIVE

To compare clinical outcomes among patients with high-risk prostate cancer after definitive treatment.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study included patients with high-risk prostate cancer (as defined by the National Comprehensive Cancer Network [NCCN]) and at least 1 adverse clinicopathologic feature (defined as any primary Gleason pattern 5 on biopsy, clinical T3b-4 disease, ≥50% cores with biopsy results positive for prostate cancer, or NCCN ≥2 high-risk features) treated between 2000 and 2014 at 16 tertiary centers. Data were analyzed in November 2020.

EXPOSURES

Radical prostatectomy (RP), external beam radiotherapy (EBRT) with androgen deprivation therapy (ADT), or EBRT plus brachytherapy boost (BT) with ADT. Guideline-concordant multimodal treatment was defined as RP with appropriate use of multimodal therapy (optimal RP), EBRT with at least 2 years of ADT (optimal EBRT), or EBRT with BT with at least 1 year ADT (optimal EBRT with BT).

MAIN OUTCOMES AND MEASURES

The primary outcome was prostate cancer-specific mortality; distant metastasis was a secondary outcome. Differences were evaluated using inverse probability of treatment weight-adjusted Fine-Gray competing risk regression models.

RESULTS

A total of 6004 men (median [interquartile range] age, 66.4 [60.9-71.8] years) with high-risk prostate cancer were analyzed, including 3175 patients (52.9%) who underwent RP, 1830 patients (30.5%) who underwent EBRT alone, and 999 patients (16.6%) who underwent EBRT with BT. Compared with RP, treatment with EBRT with BT (subdistribution hazard ratio [sHR] 0.78, [95% CI, 0.63-0.97]; P = .03) or with EBRT alone (sHR, 0.70 [95% CI, 0.53-0.92]; P = .01) was associated with significantly improved prostate cancer-specific mortality; there was no difference in prostate cancer-specific mortality between EBRT with BT and EBRT alone (sHR, 0.89 [95% CI, 0.67-1.18]; P = .43). No significant differences in prostate cancer-specific mortality were found across treatment cohorts among 2940 patients who received guideline-concordant multimodality treatment (eg, optimal EBRT alone vs optimal RP: sHR, 0.76 [95% CI, 0.52-1.09]; P = .14). However, treatment with EBRT alone or EBRT with BT was consistently associated with lower rates of distant metastasis compared with treatment with RP (eg, EBRT vs RP: sHR, 0.50 [95% CI, 0.44-0.58]; P < .001).

CONCLUSIONS AND RELEVANCE

These findings suggest that among patients with high-risk prostate cancer and additional unfavorable clinicopathologic features receiving guideline-concordant multimodal therapy, prostate cancer-specific mortality outcomes were equivalent among those treated with RP, EBRT, and EBRT with BT, although distant metastasis outcomes were more favorable among patients treated with EBRT and EBRT with BT. Optimal multimodality treatment is critical for improving outcomes in patients with high-risk prostate cancer.

Integrating Prostate-specific Antigen Kinetics into Contemporary Predictive Nomograms of Salvage Radiotherapy After Radical Prostatectomy

BACKGROUND

Salvage radiotherapy (SRT) is an established treatment for men with biochemical recurrence following radical prostatectomy (RP). There are several risk factors associated with adverse outcomes; however, the value of postoperative prostate-specific antigen (PSA) kinetics is less clear in the ultrasensitive PSA era.

OBJECTIVE

To characterize the impact of PSA kinetics on outcomes following SRT and generate nomograms to aid in identifying patients with an increased risk of adverse clinical outcomes.

DESIGN, SETTING, AND PARTICIPANTS

A multi-institutional analysis was conducted of 1005 patients with prostate cancer treated with SRT after RP, with a median follow-up of 5 years.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Variables examined include immediate postoperative PSA, postoperative PSA doubling time (DT), and pre-SRT PSA, in addition to previously identified predictive factors. Multivariable survival analyses were completed using Fine-Gray competing risk regression. Rates of biochemical failure (BF), distant metastasis (DM), and prostate cancer-specific mortality (PCSM) were estimated by the cumulative incidence method. Nomograms were generated from multivariable competing risk regression with bootstrap cross-validation.

RESULTS AND LIMITATIONS

Factors associated with BF after SRT include PSA DT <6 mo, initial postoperative PSA ≥0.2 ng/ml, higher pre-SRT PSA, lack of androgen deprivation therapy, a higher Gleason score (GS), negative margins, seminal vesicle invasion, lack of pelvic nodal radiation, radiation total dose <66 Gy, a longer RP to SRT interval, and older age (p < 0.05 for each). Factors associated with DM include PSA DT <6 mo, pre-SRT PSA, a higher GS, and negative margins. Factors associated with PCSM include PSA DT not calculable or <6 mo and a higher GS. Nomograms were generated to estimate the risks of BF (concordance index [CI] 0.74), DM (CI 0.77), and PCSM (CI 0.77). Limitations include retrospective nature, broad treatment eras, institutional variations, and multiple methods available for the estimation of PSA DT.

CONCLUSIONS

Postoperative PSA kinetics, particularly pre-SRT PSA and PSA DT, are strongly associated with adverse oncologic outcomes following SRT and should be considered in management decisions.

PATIENT SUMMARY

In this report of men with prostate cancer who developed a prostate-specific antigen (PSA) recurrence after prostatectomy, we found that PSA levels after surgery and how quickly a PSA level doubles significantly impact the chance of prostate cancer recurrence after salvage radiation therapy. Based on this information, we created a tool to calculate a man's chance of cancer recurrence after salvage radiation therapy, and these estimations can be used to discuss whether additional treatment with radiation should be considered.

No Longer a Match: Trends in Radiation Oncology National Resident Matching Program (NRMP) Data from 2010-2020 and Comparison Across Specialties

PURPOSE

To report trends in the number and types of applicants and matched trainees to radiation oncology in comparison to other specialties participating in the National Resident Matching Program (NRMP) between 2010 and 2020.

METHODS AND MATERIALS

Data from the NRMP and Electronic Residency Application System (ERAS) were obtained for 18 medical specialties between 2010 and 2020. We assessed the numbers and types of applicants and matched trainees relative to available positions in the NRMP and Supplemental Offer and Acceptance Program (SOAP).

RESULTS

In the 2020 NRMP, 122 US MD senior graduates preferentially ranked radiation oncology, a significant decrease from a median of 187 between 2010 to 2019 (interquartile range [IQR], 170-192; P < .001). Across all 18 specialties, radiation oncology experienced the greatest declines in the 2020 NRMP cycle relative to 2010 to 2019, in both the number of ERAS applicants from the United States and Canada (-31%) and the percentage of positions filled by US MD or DO senior graduates (-28%). Of 189 available positions, 81% (n = 154) filled in the NRMP prior to the SOAP, of which 65% (n = 122) were "matched" by US MD senior graduates who preferentially ranked radiation oncology as their top choice of specialty, representing a significant decrease from a median of 92% between 2010 to 2019 (IQR, 88%-94%; P = .002). The percentages of radiation oncology programs and positions unfilled in the NRMP prior to the SOAP were significantly increased in 2020 compared with 2010 to 2019 (programs: 29% vs 8% [IQR, 5%-8%; P < .001]; positions: 19% vs 4% [IQR, 2%-4%; P <.001]). Despite >99% (n = 127 of 128) of US MD or DO senior applicants preferring radiation oncology successfully matching to a radiation oncology position in the 2020 NRMP, 16 of 35 remaining unfilled positions were filled via the SOAP. Radiation oncology was the top user of the SOAP across all specialties participating in the 2020 NRMP, filling 15% of total positions versus a median of 0.9% (IQR, 0.3%-2.3%; P <.001).

CONCLUSIONS

The supply of radiation oncology residency positions now far exceeds demand by graduating US medical students. Efforts to nullify a market correction revealed by medical student behavior via continued reliance on the SOAP to fill historical levels of training positions may not be in the best of interest of trainees, individual programs, or the specialty as a whole.

Radiation Oncology Resident Quality by National Resident Matching Program Metrics From 2007 to 2018

PURPOSE

To quantify how the quality of US medical students accepted to radiation oncology (RO) training programs, as defined by National Resident Matching Program (NRMP) metrics, has changed over time.

METHODS AND MATERIALS

We examined NRMP data of senior US medical students matched into RO training programs from 2007 to 2018. Metrics include United States Medical Licensing Exam (USMLE) Step 1 and 2-Clinical Knowledge scores, research output, percentage with PhD, and percentage in Alpha Omega Alpha (AOA), among others. Linear regression analysis assessed the statistical significance of changes in available metrics of matched RO residents over time. The Student t test and χ² test compared quality metrics between matched students in RO versus all other specialties.

RESULTS

From 2007 to 2018, the mean USMLE Step 1 and 2-Clinical Knowledge for RO residents significantly increased from 235 to 247 (1.0 point/year; 95% confidence interval [CI], 0.70-1.52; P = .002) and from 237 to 253 (1.3 points/year; 95% CI, 1.27-1.62; P <.001), respectively. The mean number of research experiences and abstracts/presentations/publications increased from 3.7 to 6.1 (0.2/year; 95% CI, 0.12-0.29; P = .003) and from 6.3 to 15.6 (0.78/year; 95% CI, 0.60-1.04; P <.001), respectively. The percentage of RO residents inducted into AOA increased from 24.2% to 35.2%, whereas those with a PhD remained stable (∼21%). Matched RO residents had statistically superior metrics versus all other specialties for USMLE Step 1 scores (mean +13.5 points; 95% CI, 7.26-19.67; P <.001), research experience (mean +2.04; 95% CI, 1.11-2.97; P <.001), abstracts/presentations/publications (mean +6.80; 95% CI, 3.38-10.22; P = .001), percentage with a PhD (22.2% vs 4.1%; P <.001), and percentage in AOA (29.5% vs 15.8%; P <.001).

CONCLUSIONS

RO resident quality, defined by routinely reported NRMP metrics, increased from 2007 to 2018. Furthermore, RO resident quality is significantly higher than in all other specialties combined for most metrics. Whether the recent decline in medical student interest in RO will correlate with reduced NRMP quality metrics is unknown.

TARGIT-R (Retrospective): 5-Year Follow-Up Evaluation of Intraoperative Radiation Therapy (IORT) for Breast Cancer Performed in North America

BACKGROUND

Intraoperative radiation therapy (IORT) has been investigated for patients with low-risk, early-stage breast cancer. The The North American experience was evaluated by TARGIT-R (retrospective) to provide outcomes for patients treated in "real-world" clinical practice with breast IORT. This analysis presents a 5-year follow-up assessment.

METHODS

TARGIT-R is a multi-institutional retrospective registry of patients who underwent lumpectomy and IORT between the years 2007 and 2013. The primary outcome of the evaluation was ipsilateral breast tumor recurrence (IBTR).

RESULTS

The evaluation included 667 patients with a median follow-up period of 5.1 years. Primary IORT (IORT at the time of lumpectomy) was performed for 72%, delayed IORT (after lumpectomy) for 3%, intended boost for 8%, and unintended boost (primary IORT followed by whole-breast radiation) for 17% of the patients. At 5 years, IBTR was 6.6% for all the patients, with 8% for the primary IORT cohort and 1.7% for the unintended-boost cohort. No recurrences were identified in the delayed IORT or intended-boost cohorts. Noncompliance with endocrine therapy (ET) was associated with higher IBTR risk (hazard ratio [HR], 3.67). Patients treated with primary IORT who were complaint with ET had a 5-year IBTR rate of 3.9%.

CONCLUSION

The local recurrence rates in this series differ slightly from recent results of randomized IORT trials and are notably higher than in previous published studies using whole-breast radiotherapy for similar patients with early-stage breast cancer. Understanding differences in this retrospective series and the prospective trials will be critical to optimizing patient selection and outcomes going forward.

Outcomes with Partial Breast Irradiation vs. Whole Breast Irradiation: a Meta-Analysis

BACKGROUND

Several randomized trials have been performed comparing partial breast irradiation (PBI) and whole breast irradiation (WBI) though controversy remains, including regarding differences by PBI technique. We performed a meta-analysis to compare results between WBI versus PBI and between PBI techniques.

METHODS

A systematic review was performed to identify modern randomized studies listed in MEDLINE from 2005 to 2020. PBI trials were divided into external beam radiation and brachytherapy techniques, with intraoperative radiation excluded. A Bayesian logistic regression model evaluated the risk of ipsilateral breast tumor recurrence (IBTR) and acute and chronic toxicities. The primary outcome was IBTR at 5 years with WBI compared with PBI.

RESULTS

A total of 9758 patients from 7 studies were included (4840-WBI, 4918-PBI). At 5 years, no statistically significant difference in the rate of IBTR was noted between PBI (1.8%, 95% HPD 0.68-3.2%) and WBI (1.7%, 95% HPD 0.92-2.4%). By PBI technique, the 5-year rate of IBTR rate for external beam was 1.7% and 2.2% for brachytherapy. Rates of grade 2 + acute toxicity were 7.1% with PBI versus 47.5% with WBI. For late toxicities, grade 2/3 rates were 0%/0% with PBI compared with 1.0%/0% with WBI.

CONCLUSIONS

IBTR rates were similar between PBI and WBI with no significant differences noted by PBI technique; PBI had reduced acute toxicities compared to WBI. Because studies did not provide toxicity data in a consistent fashion, definitive conclusions cannot be made with additional data from randomized trials needed to compare toxicity profiles between PBI techniques.

Treatment Options in Oligometastatic Disease in Prostate Cancer: Thinking Outside the Box

OPINION STATEMENT

Due to its relatively indolent disease course, the sensitivity of PSA testing, and the emergence of novel PET imaging, metastatic prostate cancer is particularly likely to present with a limited volume of disease. Patients with up to five metastatic lesions should be considered for an oligometastatic treatment approach. Systemic therapy remains the cornerstone of treatment for these patients. The optimal type and duration are unknown; however, the addition of a second agent to ADT appears to be beneficial. Multiple recent studies have found significant benefits to the integration of systemic therapy and local metastasis-directed therapies (MDT), including radiation and surgery, to the prostate and metastatic sites. MDT may also be used in select patients wishing to delay the initiation of systemic therapy. For patients with isolated regional nodal recurrences, whole pelvic radiotherapy or extensive lymphadenectomy is preferred, in combination with ADT.

A novel orthotopic murine model of neuroendocrine bladder cancer: Insights into the phenotypic plasticity of small cell bladder cancer (SCBC)

571

Background: SCBC is an aggressive subtype of bladder cancer with high metastatic potential and few effective treatment options. We developed an orthotopic mouse model of SCBC to understand the development of this rare bladder cancer variant and identify epigenetic drivers of neuroendocrine differentiation. Methods: Lentiviral particles carrying Cre recombinase were produced using Lenti-sgNeo#2/Cre. The bladders of Rb1fl/fl Trp53fl/fl MycLSL/LSL (RPM) mice was transduced with Cre recombinase expressing lentivirus via transurethral catheterization. Mice were monitored by micro-ultrasound (mUS) and detected tumors were verified by histology. SCBC morphology was confirmed by H&E staining and synaptophysin IHC. Whole transcriptome (RNAseq) analysis was performed to correlate transcriptomic profile of neuroendocrine mouse tumors to a cohort of human SCBC tumors. Results: Transurethral catheterization successfully transduced the bladder urothelium without evidence of exposure of ectopic (non-urothelial) tissues. RPM mice developed SCBC visible on mUS with a latency of 8-10 weeks. As expected in neuroendocrine tumors, mice developed liver and lung metastases. High grade neuroendocrine morphology and NE markers were confirmed on H&E and IHC, respectively, by a GU pathologist. Western blot analysis confirmed cMyc expression and suppression of TP53 and RB1. Synaptophysin expression was confirmed by IHC. Transcriptomic profiling of both mouse and human SCBC demonstrated concordant gene expression. Gene expression profiling of urothelial and non-urothelial neuroendocrine tumors suggested a phenotypic convergence. Conclusions: We developed a novel genetically engineered murine model of SCBC. Ongoing work seeks to identify epigenetic markers playing role in the development of this aggressive variant of bladder cancer. We are assessing the activity of immune checkpoint inhibitors in this immunocompetent background.

Tumor cell intrinsic androgen biosynthesis by 3β-hydroxy steroid dehydrogenase (HSD3B1) to modulate radiosensitivity in prostate cancer cells

349

Background: Resistance to ADT is associated with a gain of function mutation in the 3β-HSD enzyme, which catalyzes extragonadal/intratumoral DHT synthesis. As androgen signaling is known to upregulate the DNA damage response (DDR), we investigated whether HSD3B1 genotype modulates DDR and radiosensitivity in PCa. Methods: We stably knocked down HSD3B1 in LNCaP, C42 and VCaP cell lines (which carry the protein stabilizing variant allele) and overexpressed the variant HSD3B1 allele in LAPC4 (harbors a WT allele which readily undergoes degradation). We examined the proliferative and clonogenic capacity of these cells in presence and absence of substrate, DHEA, followed by treatment with IR (400-800 cGy, single fraction). We studied DNA DSB formation and resolution kinetics using γH2AX foci formation in response to radiation. We also measured changes in mRNA expression of DDR response genes pre- and post-radiation. Results: Control shRNA transduced cell lines had increased cell proliferation (p<0.001) and clonogenic survival (2 logs at 800cGy single fraction radiation, p<0.001) in the presence of DHEA compared to HSD3B1 knockdown cells. Variant HSD3B1 cell lines were more radioresistant and exhibited more efficient γH2AX foci resolution at 24 hrs (p <0.05) in a DHEA dependent manner. We observe increased mRNA expression of DDR genes from specific repair networks including non-homologous end joining (PRKDC, XRCC4, XRCC5) and homologous recombination (RAD51, RAD54) in variant HSD3B1 cells. Transcriptional induction of DDR genes following radiation in presence of DHEA was significantly more pronounced in HSD3B1 variant cells, suggesting a more permissive chromatin context. Conclusions: Increased intracellular 3β-HSD drives transcription of NHEJ and HR genes, more rapid resolution of γH2AX foci, and radioresistance in prostate cancer. This work has therapeutic implications related to strategies for combined radiation and androgen directed therapy in localized and metastatic prostate cancer. Prospective validation of treatment strategies combining blockade of adrenal steroid precursor synthesis, ADT, and XRT in high risk disease is warranted.

Impact of initial treatment selection on clinical outcomes after biochemical failure in radiorecurrent high-risk prostate cancer

208

Background: Treatment of high risk prostate cancer (HRPCa) with external beam radiotherapy (EBRT) plus brachytherapy (BT) boost (EBRT+BT) has been prospectively associated with lower rates of BCR, albeit potentially with increased toxicity, and retrospectively linked to decreased distant metastasis (DM) and PCa-specific mortality (PCSM) compared to EBRT alone. However, it is unclear whether patients who develop BCR following either approach have similar downstream oncologic outcomes. Methods: We identified 706 out of 3820 men with HRPCa treated at 13 institutions from 1998-2015 with EBRT (n=468/2134) or EBRT+BT (n=238/1686) who developed BCR. We compared rates of DM, PCSM, and all-cause mortality (ACM) after BCR between treatment groups using Fine-Gray competing risk regression. Models were adjusted for age, Gleason grade group, initial PSA (iPSA), clinical T stage, time-dependent use of systemic salvage, and interval to BCR using inverse probability of treatment weighting. Results: Median follow-up was 9.9 years from RT and 4.8 years from BCR. Groups were similar in age, iPSA, presence of ≥2 HR features, and median interval to BCR (3.3 years). Most men received neoadjuvant/concurrent androgen deprivation therapy (ADT), 92.5% and 91.0% for EBRT and EBRT+BT, respectively, though for a longer duration with EBRT (median 14.7 vs. 9.0 months, p=0.0012). Local and systemic salvage rates were 2.3% and 36.3% after EBRT, and 2.6% and 43.6% after EBRT+BT, respectively. Initial EBRT+BT was associated with significantly lower rates of DM after BCR (HR 0.48, 95% CI 0.36-0.64, p<0.001). Rates of PCSM and ACM did not significantly differ (HR 0.93, 95% CI 0.67-1.30, p=0.93, and HR 0.8, 95% CI 0.6-1.1, p=0.11, respectively). Conclusions: In this large retrospective series of radiorecurrent HRPCa, initial treatment with EBRT+BT was associated with significantly lower rates of DM after BCR compared with EBRT, despite shorter ADT use and a similar median interval to BCR. Local salvage was widely underutilized in both groups. In the absence of salvage for local failure after EBRT, upfront treatment intensification with BT may reduce DM, though not PCSM or ACM, even after development of BCR.

Long-term complications and reconstruction failures in previously radiated breast cancer patients receiving salvage mastectomy with autologous reconstruction or tissue expander/implant-based reconstruction

Salvage mastectomy (SM) is the standard of care for patients with local recurrence (LR) after breast conservation therapy (BCT), often with immediate reconstruction. Complications of reconstruction are a concern for these patients, and long-term data are limited. We sought to compare rates of complications requiring re-operation (CRR) and reconstruction failure (RF) between autologous reconstruction (AR) and tissue expander/implant reconstruction (TE/I). Patients with locally recurrent breast cancer after BCT, treated with SM and immediate AR or TE/I between 2000 and 2008, were identified. CRR was defined as unplanned return to operating room for wound infection, dehiscence, necrosis (including flap, skin, or fat), hematoma, or hernia (for AR) and extrusion, leak, or capsular contracture (for TE/I). RF was defined as conversion to another reconstruction technique or to flat chest wall. This study included 103 patients with 107 reconstructions. Median follow-up was 6.6 years. CRR and RF were significantly higher with TE/I (n = 34) compared to AR (n = 73) at 5 years (50.9% vs 25.5%; P = 0.02) and (42.1% vs 5.8%; P < 0.001). On univariate analysis (UVA), TE/I (HR = 2.14; P = 0.02) and diabetes (HR = 5.10; P = 0.007) were significant predictors for CRR. On UVA, TE/I (HR = 7.30; P < 0.001) and older age at reconstruction (HR = 1.03; P = 0.003) were significant predictors for RF. In this population of previously irradiated patients, TE/I was associated with significantly higher CRR and RF. Complications continue to occur up to 10 years after TE/I. AR should be considered in appropriately selected patients, though TE/I may remain a reasonable option in patients without high-risk factors for surgical complications.

Association of cell-free DNA (cfDNA) levels with myeloid-derived suppressor cells (MDSC) levels in blood of patients (pts) with muscle invasive (MI) and metastatic (met) bladder cancer (BC)

4528

Background: cfDNA can be detected in healthy individuals but higher concentrations are present in pts with cancer. MDSC are immature immunosuppressive cells that can be mobilized from bone marrow by tumor-related factors. Higher blood MDSC levels have been associated with worse outcomes in pts with solid tumors including BC. We assessed correlations between cfDNA and MDSC levels in pts with MIBC and met BC. Methods: Peripheral blood from pts with MIBC and met BC was collected in Streck BCT tubes and processed to obtain cf nucleic acid extracts. Total cfDNA was determined by fluorimetry. Cell-free DNA fragment size was measured by Bioanalyzer DNA analysis; 100-400 bp fragments (mono- and di-nucleosomal fragments linked to granulocytic processing of apoptotic and necrotic tumor cells) were designated low molecular weight (LMW-frags). The % of MDSC (CD33+/HLADR-) and subtypes were measured. MDSC subtypes were defined as polymorphonuclear (PMN-MDSC: CD15+/CD14-), monocytic (M-MDSC: CD15-/CD14+) and uncommitted (UNC-MDSC: CD15-/CD14-). Spearman’s correlation test was used for analysis. Results: Blood from 37 pts (19% women, 40% never smokers) with MIBC or met BC was collected: 15 (41%) with MIBC and 22 (59%) with met BC at time of collection. There was a significantly positive correlation between total MDSC and cfDNA levels (r = 0.57, P = 0.0003). Among MDSC subtypes, there was a significantly positive correlation between PMN-MDSC and cfDNA levels (r = 0.61, P < 0.0001). The higher level of LMW-frags was significantly but moderately associated with higher total MDSC (r = 0.43, P 0.008) and PMN-MDSC (r = 0.41, P 0.01) levels. There was no significant correlation between cfDNA level and other MDSC subtypes. Conclusions: There was a positive correlation between total and PMN-MDSC with cfDNA levels in blood from pts with MIBC and met BC. That may suggest a putative role for MDSC in mediating cfDNA release into the circulation, consistent with prior reports of granulocyte-mediated ctDNA processing. Further studies need to identify mechanisms and implications of our findings and potential correlation with clinical outcomes.

Circulating cell-free DNA (cfDNA) levels and fragmentation pattern can distinguish nonmuscle invasive (NMI) from muscle-invasive (MI) and metastatic (met) bladder cancer (BC)

4523

Background: Occult MI and met BC may be under-staged. Circulating cfDNA may be a dynamic, low-cost and minimally invasive biomarker. We evaluated correlations between total circulating cfDNA and presence of MIBC and met BC. We hypothesized that the relative abundance of circulating low molecular weight cfDNA would correlate with BC stage. Methods: Peripheral blood from pts with BC was collected in Streck BCT tubes and processed to obtain cf nucleic acid extracts. Total cfDNA quantity (ng/ml) was assessed by fluorimetry. cfDNA fragment size was measured by Bioanalyzer DNA analysis. Wilcoxon rank sum test and Fisher’s Exact test were used to compare cfDNA quantity and fragmentation pattern among pts with NMIBC, MIBC, met BC. Results: Blood was obtained from 58 pts with BC (20% women, 34% never smokers, median age 71 (29-89). There was no significant difference in cfDNA between MIBC and met BC, however, it was significantly lower in pts with NMIBC vs MIBC and met BC (table). The concentration of low molecular weight fragments (LMW-frags) (100 - 400) base pairs and the ratio of LMW-Frag to cfDNA were significantly different between pts with NMIBC and pts with MIBC or met BC (table). Using median values as the cutoff, there was a significantly higher proportion of pts with cfDNA > 7 ng/ml and LMW-frags > 1.6 ng/mL, in MIBC & met BC vs NMIBC (p < 0.001). The % of pts with LMW-frags to cfDNA > 30%, was significantly different among NMIBC, MIBC and met BC groups: 16%, 53%, 78%, respectively (p < 0.001). Conclusions: This exploratory study suggests that cfDNA levels may correlate with BC stage. Measuring the relative abundance of LMW-frags with the expected size of cf DNA can enhance the specificity of cfDNA analysis for distinction between MIBC and met BC. Further studies are needed to confirm findings and define the optimal cut-points for optimal BC staging. [Table: see text]

Moderately hypofractionated radiotherapy for localized prostate cancer: Long-term outcomes for 854 consecutive patients treated over 10 years (70 Gy in 2.5 Gy/fraction)

78

Background: Moderately hypofractionated radiotherapy has been increasingly adopted in the management of localized prostate cancer (PCa). We report 10-year outcomes for patients treated with intensity modulation radiation therapy (IMRT) for localized PCa with 70 Gy in 28 fractions at 2.5 Gy/fraction. Methods: This retrospective study included 854 consecutive patients with localized PCa treated with image-guided moderately hypofractionated IMRT at a single institution between 1998 and 2012. Patients with a single intermediate-risk factor were considered to have favorable intermediate-risk (FIR) disease; multiple intermediate-risk factors were considered unfavorable (UIR). Biochemical relapse free survival (bRFS), clinical relapse free survival (cRFS), overall survival (OS) and PCa specific mortality (PCSM) were analyzed used Kaplan-Meier analysis. Grade ≥3 genitourinary (GU) and gastrointestinal (GI) toxicities were recorded (CTCAE v4.03). Results: The median follow-up was 11.3 years (Max. 19 years). For patients with low-risk (LR, 31%), FIR (28%), UIR (12.5%), and high-risk (HR, 28.5%) disease the 10 year bRFS rates were 88%, 78%, 71% and 42%, respectively (p < 0.0001). The number of patients receiving no ADT, 1-6 months, or > 6 months of ADT were 39%, 50%, and 11%, respectively, reflecting practice patterns during this treatment period. The 10-year cRFS were 95%, 91%, 85% and 72% for patients with LR, FIR, UIR, and HR, respectively (p < 0.0001). The 10-year actuarial OS rate was 69% (95% CI 66-73%) and the 10-year PCSM was 6.8% (95% CI 5.1-8.6%) overall. For patients with LR, FIR, UIR and HR disease, the 10 year PCSM rates were 2%, 5%, 5% and 15%. 10-year cumulative incidence of grade ≥3 GU and GI toxicity was 2% and 1%, respectively. Multivariate analysis identified associations between clinical variables (ADT use, PSA nadir < 0.5ng/ml, and ISUP Grade Group) and bRFS, cRFS, and PCSM. Conclusions: Moderately hypofractionated IMRT with daily image guidance for localized PCa demonstrates favorable 10-year oncologic outcomes with a low incidence of toxicity for patients across all risk groups.

The effect of the timing of biochemical failure after external beam radiotherapy or low-dose-rate brachytherapy for definitive prostate cancer treatment

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Background: To assess the effect of the timing of biochemical failure (bF) after definitive radiotherapy with external beam (EBRT) or low dose-rate brachytherapy (LDR) on clinical failure (cF) and prostate cancer-specific mortality (PCSM). Methods: From 1996 to 2009, 4478 patients were treated and by 2010, 456 patients were noted to have a bF. They were categorized as early (< 5 years post-therapy) or late (≥ 5 years post-therapy) failures. Factors thought to influence cF and PCSM were scored. Cox regression was used to assess the timing of bF on cF and Fine and Gray regression was used to assess the timing of bF on PCSM. Results: There were 330 (72.4 %) patients categorized as early and 126 (27.6 %) as late failures. The median PSA follow-up post-radiotherapy for the early bF group is 82 months vs. 155 months for the late bF group, and the median PSA follow-up post-bF is 54 months for the early bF group vs. 69 months for the late bF group. The early failures were more likely to be high-risk (p = 0.0080), have a higher Gleason score (p = 0.0008), and use ADT (p = 0.0325). The five-year rate of cF post early bF is 61% vs 43% post late bF (p <0.0001). The five-year rate of PCSM post early bF is 27% vs 9% post late bF (p <0.0001). The multivariable analyses assessing the cF and PCSM are shown in Table. Conclusions: Early bF is associated with higher rates of cF and PCSM. Patients treated with LDR have a lower risk of PCSM. [Table: see text]

Identification of gene expression determinants of radiosensitivity in bladder cancer (BCa) cell lines

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Background: Trimodality therapy with TURBT followed by concurrent chemoradiation is an alternative to cystectomy in selected patients with muscle invasive BCa. Identifying genetic determinants of radiation response may help select patient for organ-sparing treatments with curative intent. Methods: Molecular characterization of 20 cell lines was previously performed, including mutation analysis, CNA (high density SNP arrays) and gene expression (RNAseq). Cell line identity was authenticated by genomic fingerprinting. We performed colony forming assays (CFA) and cumulative survival was quantified using the area under the cell survival curve (AUC, range 0-8Gy) to create a radiosensitivity index. Pre and post-radiation proliferative capacity was determined by cell titer glo (CTG) assay. Gene (R v3.5.1) and network (Ingenuity Pathyway Analysis) level expression differences were determined as a function of AUC to identify biologically relevant associations with radiation response. Results: Of 20 cell lines (7 basal, 13 luminal subtype), both CFA and CTG data was successfully obtained for 13 cell lines (6 basal, 7 luminal) treated with high dose rate (HDR) radiation. AUCs for the colony forming assay (CFA) survival curves ranged 1.79-3.27. RNAseq identified 18,634 unique transcripts mapping to distinct loci and 196 genes were identified with AUC correlation p values <0.01 (FDR <0.5, mean FPKM>0.5). These genes were strongly enriched for membership in the peroxisome proliferator (PPAR) pathway (IPA, p = 9.40E-03) and STAT3 pathway (IPA, p = 1.56E-3). Validation studies confirmed PPARγ, ICAM2, JAK3, IL1B, OAS1 and OAS2 genes to be associated with differential response to radiation, with expression upregulated in radio-resistant cells. A basal subtype was strongly associated with a radiosensitive phenotype (Chi-Squared χ2 p=0.0083). Conclusions: BCa radio-sensitivity was associated with baseline gene expression differences in vitro. The basal subtype and repression of either the PPAR or STAT3 pathways predicted increased radiosensitivity. This study nominates candidate biomarkers for mechanistic studies and clinical validation in BCa.

Ten-Year Outcomes of Moderately Hypofractionated (70 Gy in 28 fractions) Intensity Modulated Radiation Therapy for Localized Prostate Cancer

PURPOSE

Long-term outcomes with hypofractionated radiation therapy for prostate cancer are limited. We report 10-year outcomes for patients treated with intensity modulated radiation therapy (IMRT) for localized prostate cancer with 70 Gy in 28 fractions at 2.5 Gy per fraction.

METHODS AND MATERIALS

The study included 854 consecutive patients with localized prostate cancer treated with moderately hypofractionated IMRT and daily image guidance at a single institution between 1998 and 2012. Patients with a single intermediate risk factor were considered to have favorable intermediate-risk (FIR) disease, and those with multiple intermediate risk factors were considered unfavorable (UIR). Biochemical relapse-free survival, clinical relapse-free survival, and overall survival were analyzed using Kaplan-Meier analysis. Prostate cancer-specific mortality (PCSM) was analyzed using competing risk regression. All grade ≥3 genitourinary (GU) and gastrointestinal (GI) toxicities were recorded using Common Terminology Criteria for Adverse Event version 4.03, and cumulative incidence rates of GU and GI toxicity were calculated.

RESULTS

The median follow-up was 11.3 years (maximum, 19 years). For patients with low-risk (LR), FIR, UIR, and high-risk (HR) disease, the 10-year biochemical relapse free survival rates were 88%, 78%, 71%, and 42%, respectively, (P < .0001). The 10-year clinical relapse free survival were 95%, 91%, 85%, and 72% for patients with LR, FIR, UIR, and HR, respectively, (P < .0001). For all patients, the 10-year actuarial overall survival rate was 69% (95% confidence interval, 66%-73%), and the 10-year PCSM was 6.8% (95% confidence interval, 5.1%-8.6%) overall. For patients with LR, FIR, UIR and HR disease, the 10-year PCSM rates were 2%, 5%, 5%, and 15%. Long-term grade ≥3 GU or GI toxicity remained low with 10-year cumulative incidences of 2% and 1%, respectively.

CONCLUSIONS

High-dose moderately hypofractionated IMRT with daily image guidance for localized prostate cancer demonstrates favorable 10-year oncologic outcomes with a low incidence of toxicity. This fractionation schedule appears to be acceptable for patients across all risk groups.

Trends in Radiation Oncology Residency Applicant Interview Experiences and Post-Interview Communication

PURPOSE

To report trends in applicant interview experiences and post-interview communication (PIC) between the 2016 and 2018 radiation oncology interview cycles.

METHODS AND MATERIALS

An anonymous survey was sent to all 203 residency applicants to a single institution during the 2018 Match, and the results were compared to a similar 2016 survey.

RESULTS

Response rates in 2018 and 2016 were 53% and 56%, respectively. Applicants from 2018 were asked less frequently than 2016 applicants about where else they were interviewing (71% vs 84%, P = .024) and how highly they planned to rank a program (11% vs 23%, P = .018). A higher proportion of 2018 programs explicitly discouraged PIC (median, 53% vs 33%, P < .0001), and more 2018 respondents chose not to send any thank-you notes/emails (42% vs 17%, P < .0001). When comparing 2018 results to 2016, no significant differences were observed in the proportion of applicants who notified their top program that they would rank that program highly (54% vs 60%, P = .354). No difference was observed in the rate of reported distress associated with a sense of obligation to send PIC (49% vs 46%, P = .664), and similar rates of respondents said they would feel relieved if PIC was discouraged (94% vs 89%, P = .223). Most respondents again reported that they would prefer a policy to actively discourage applicants from notifying their top programs of their high rank (60% vs 66%, P = .974).

CONCLUSIONS

Compared to 2016, respondents in 2018 reported that fewer programs are engaging in potential Match violations, and more are actively discouraging PIC, possibly as a result of increased awareness from recent publications. A similar number of applicants continued to engage in "gamesmanship," but more are choosing not to send thank-you notes/emails. Most respondents continue to prefer a policy discouraging PIC.

Oncotype testing in patients undergoing intraoperative radiation for breast cancer

Oncotype DX recurrence score (RS) predicts risk of distant disease recurrence, and can guide chemotherapy recommendations in hormone positive, human epidermal growth factor 2-negative, early stage breast cancer. The present study aimed to evaluate the pattern of oncotype testing, RS and adjuvant treatment in patients undergoing intraoperative radiotherapy (IORT). Single center prospective data registry was queried for patients receiving IORT between October 2011 and February 2017. Patient demographics, tumor characteristics, RS, systemic therapy and recurrence information were analyzed. A total of 150 women with mean age of 70.8 years were included. The majority had invasive ductal cancer (60.6%) with 1.0 cm average tumor size and no lymph node involvement (99%). Oncotype testing was performed in 36 patients (24.3%). Low risk score (<18) was confirmed in 19 women (53%); intermediate risk score (18-30) in 16 women (44%); and high risk score (>30) in one woman (3%). Patients with RS testing had significantly increased tumor sizes (1.2 vs. 1.0 cm; P<0.001) and were younger (68.5 vs. 71.3 years; P=0.02) compared with those not tested. A total of 4/150 patients (2.6%) received chemotherapy; two received chemotherapy based on RS testing. Based on the current selection criteria for IORT, oncotype testing rarely results in a high-risk score or utilization of chemotherapy for IORT patients. The present study supports selective use of RS testing in IORT patients and confirms that biologically low-risk patients are being selected for IORT based on current guidelines.

The Residency Match: Interview Experiences, Postinterview Communication, and Associated Distress

BACKGROUND

Interview experiences and postinterview communication during the residency match process can cause distress for applicants, and deserve further study.

OBJECTIVE

We both quantified and qualified the nature of various interview behaviors during the 2015-2016 National Resident Matching Program (NRMP) Match and collected applicant perspectives on postinterview communication and preferences for policy change.

METHODS

An anonymous, 31-question survey was sent to residency candidates applying to 8 residency programs at a single academic institution regarding their experiences at all programs where they interviewed.

RESULTS

Of 6693 candidates surveyed, 2079 (31%) responded. Regarding interview experiences, applicants reported being asked at least once about other interviews, marital status, and children at the following rates: 72%, 38%, and 17%, respectively, and such questions arose at a reported mean of 25%, 14%, and 5% of programs, respectively. Female applicants were more frequently asked about children than male applicants (22% versus 14%, P < .0001). Overall, 91% of respondents engaged in postinterview communication. A total of 70% of respondents informed their top program that they had ranked it highly; 70% of this subset reported associated distress, and 78% reported doing this to improve match success. A total of 71% would feel relief if postinterview communication was actively discouraged, and 51% would prefer applicants to be prohibited from notifying programs of their rank.

CONCLUSIONS

Applicants to several residency programs reported being asked questions that violate the NRMP Code of Conduct. The majority of applicants would prefer postinterview communication to be more regulated and less prevalent.

Optimizing the Timing of Salvage Postprostatectomy Radiotherapy and the Use of Concurrent Hormonal Therapy for Prostate Cancer

CONTEXT

Currently, salvage radiotherapy (SRT) is the only known curative intervention for men with recurrent disease following prostatectomy. Critical issues in the optimal selection and management of men being considered for SRT include the threshold prostate-specific antigen (PSA) value at which to initiate treatment (ie, pre-SRT PSA) and the role of concurrent hormonal therapy (HT).

OBJECTIVE

To review the published evidence pertaining to the optimal timing for SRT and the role of concurrent HT.

EVIDENCE ACQUISITION

MEDLINE (via PubMed), EMBASE, the Cochrane Central Register of Controlled Trials, and guideline statements from professional organizations were queried from January 1, 2000 through January 10, 2018.

EVIDENCE SYNTHESIS

Thirty-three independent reports, including two randomized trials evaluating HT with SRT, were identified. Retrospective data suggest that SRT initiation at lower pre-SRT PSA levels is associated with better clinical outcomes. Prospective data suggest an overall survival benefit with concurrent HT that manifests during long-term follow-up, with the caveat that hypothesis-generating subgroup analyses suggest that this benefit may be limited to patients with higher pre-SRT PSA levels. Patients with adverse risk factors, such as Gleason grade group 4-5 disease, are likely to benefit the most from earlier SRT initiation and/or the use of HT.

CONCLUSIONS

Given the limitations of the available data, it is imperative that physicians participate in shared decision-making, with the recommendation tailored for each man's desire to maximize oncologic benefit (with a risk of overtreatment) versus potential quality-of-life optimization (with a risk of undertreatment). Within that framework, a significant body of retrospective data supports initiation of SRT at low pre-SRT PSA values, without an arbitrary absolute threshold. Prospective data suggest a benefit of HT, but this benefit may be greatest in patients with a pre-SRT PSA that is higher than the typical level in most patients receiving "early" SRT. Further research is necessary before absolute recommendations can be made.

PATIENT SUMMARY

Two ways to potentially improve outcomes following salvage radiotherapy for prostate cancer that recurs after prostatectomy are to start treatment at a lower prostate-specific antigen level and to use concurrent hormonal therapy. Our review suggests that the available evidence is imperfect, but highlights that both measures are likely to improve clinical outcomes in general, but perhaps not uniformly and/or consistently for all patients. Physician-patient shared decision-making and further research are critical.