Long-term results of the Dutch randomized prostate cancer trial: Impact of dose-escalation on local, biochemical, clinical failure, and survival

Primary Analysis of (NCT03380806) a Phase II Randomized Trial of Stereotactic Body Radiotherapy Boost Versus Conventional Fractionation External Beam Radiotherapy Boost in Unfavorable-Intermediate and High-Risk Prostate Cancer

BACKGROUND

Standard treatment for unfavorable-intermediate and high-risk prostate cancer involves androgen deprivation therapy (ADT) in combination with pelvic conventional fractionation (CF) external beam radiotherapy (EBRT) and a CF-EBRT or brachytherapy boost to the prostate. This trial compared CF-EBRT boost with stereotactic body radiotherapy (SBRT) boost after pelvic CF-EBRT.

METHODS

Patients were randomized to receive a boost using either CF-EBRT (32-34 Gy in 15-17 fractions) or SBRT (19.5-21 Gy in three weekly fractions) following pelvic CF-EBRT (45-46 Gy in 23-25 fractions). The primary objective was to assess early (3-month post-radiotherapy) gastrointestinal (GI) and genitourinary (GU) quality of life (QoL), using the expanded prostate index composite (EPIC) score. Secondary objectives included long-term QoL, International Prostate Symptom Score (IPSS) changes, toxicity assessments, and long-term disease control outcomes. Linear regression and Fisher's exact test were used for analysis.

RESULTS

Of the 100 patients randomized, 53 received CF-EBRT, and 47 received SBRT. After a mean follow-up of 18.5 months, no significant differences were observed in EPIC score changes between CF-EBRT and SBRT at 3 months posttreatment for urinary (11.5 vs. 8.6, p = 0.23), bowel (5.2 vs. 6.4, p = 0.57), and overall QoL (8.3 vs. 7.5, p = 0.61). IPSS scores were similar (p = 0.11), and CTCAE v.5.0 toxicity rates were comparable, with an odds ratio of 0.90 (p > 0.99). Biochemical failure rates were under 5% for both groups.

CONCLUSIONS

This is the first randomized trial to report QoL outcomes after SBRT boost radiotherapy in patients with unfavorable-intermediate and high-risk prostate cancer. SBRT boost after pelvic CF-EBRT is well-tolerated and demonstrates comparable outcomes in QoL and toxicity to the CF-EBRT boost. Further follow-up is needed to assess the long-term effects on QoL, toxicity, and disease control.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03380806.

Hypofractionated Dose Escalation Radiotherapy for High-Risk Prostate Cancer: the survival analysis of the Prostate Cancer Study-5 (PCS-5), a GROUQ-led phase III trial

BACKGROUND AND OBJECTIVE

Prostate Cancer Study 5 (PCS5) compared conventional fractionated radiotherapy (CFRT) with hypofractionated radiotherapy (HFRT) in high-risk prostate cancer (PCa) patients, hypothesizing similar toxicity and survival outcomes. This report presents the efficacy analysis.

METHODS

PCS5 is a Canadian multicenter, open-label, phase 3 randomized control trial. Men with histologically proven, clinically localized PCa with one or more high-risk features (T3/T4, Gleason score ≥8, and prostate-specific antigen >20) were eligible. Patients were randomized 1:1 to CFRT (76 Gy/38 fractions [Fx] to the prostate and 46 Gy/23 Fx to the pelvic lymph nodes [PLNs]) or HFRT (68 Gy/25 Fx to the prostate and 45 Gy/25 Fx to the PLNs) and 28 mo of androgen suppression. The primary endpoint was toxicity; secondary endpoints included survival outcomes.

KEY FINDINGS AND LIMITATIONS

Of 329 patients, 164 were randomized to HFRT and 165 to CFRT, with 159 in the HFRT arm and 160 in the CFRT arm included in survival analyses. At the 5-yr median follow-up, there were no significant differences in overall survival (OS; 90.3% vs 89.7%; risk ratio [RR]: 1.01; 95% confidence interval [CI]: 0.93-1.09), PCa-specific survival (PCSS; 97.4% vs 97.5%; RR: 1.00; 95% CI: 0.93-1.07), biochemical recurrence-free survival (BCRFS; 85.2% vs 85.2%; RR: 1.00; 95% CI: 0.91-1.10), or distant metastasis-free survival (DMFS; 87.1% vs 87.1%; RR: 1.00; 95% CI: 0.92-1.09). Hazard ratios were 0.92 (95% CI: 0.56-1.53) for OS, 1.31 (95% CI: 0.46-3.78) for PCSS, 0.85 (95% CI: 0.56-1.30) for BCRFS, and 0.90 (95% CI: 0.56-1.43) for DMFS. Sample size was a limiting factor.

CONCLUSIONS AND CLINICAL IMPLICATIONS

There were no differences in survival outcomes between HFRT (68 Gy/25 Fx) and CFRT (76 Gy/38 Fx). HFRT, including PLN radiotherapy and long-term androgen deprivation therapy, should be considered a new standard of care for high-risk PCa patients undergoing external beam radiotherapy.

Safety and early outcomes of proton therapy and low-dose rate brachytherapy boost for patients with prostate cancer

PURPOSE

Brachytherapy boost improves biochemical control for patients with prostate cancer. Here, we report the safety and early efficacy of proton therapy (PT) with a low-dose-rate (LDR) brachytherapy boost.

METHODS

This retrospective study included patients with intermediate- or high-risk prostate cancer treated with PT followed by LDR boost, with or without androgen deprivation therapy (ADT), from 2010 through 2023. Patient, disease, and treatment characteristics, gastrointestinal (GI) and genitourinary (GU) toxicity, and efficacy outcomes are reported.

RESULTS

Ninety-nine patients received PT and LDR boost; median age at diagnosis was 68 years (interquartile range [IQR] 61-72). Most patients (n = 77) were White, 12 were African American, 5 Asian, and 3 Hispanic. Thirty-five patients had intermediate-risk (4 favorable and 31 unfavorable), 56 had high-risk, and 8 had very high-risk disease. Median PT dose was 44 Gy(RBE) (range 40-50.4) and median LDR dose was 90Gy (range 90-110). Pd-103 seed strands were used for 95 patients and I-125 for 4; 90 had MRI-assisted radiosurgery brachytherapy; 91 received ADT; and 21 had a rectal spacer. At a median follow-up time of 45 months, 5-year biochemical recurrence-free survival was 98%. There was no local recurrence, distant metastasis, or cancer death. Four patients had acute urinary retention after brachytherapy procedure. Eleven patients (11%) had late grade 2 GU toxicity, and 3 (3%) had late grade 2 GI toxicity. One patient had grade 3 urethral stricture requiring dilatation and transurethral resection.

CONCLUSIONS

At 45 months' follow-up time, treatment with PT and LDR boost led to high control rates and low toxicity for men with prostate cancer.

« Augmented radiotherapy » in the management of high-risk prostate cancer (PCa): A systematic review

BACKGROUND

In patients with high-risk (HR) prostate cancer (PCa) treated with radiotherapy and androgen deprivation therapy (ADT), intensification with androgen receptor pathway inhibitor (ARPI) improves overall survival (OS), at the cost of significant side-effects. We hypothesized that "augmented RT" schedules (defined as either dose-escalation on the prostate gland over 78 Gy and/or addition of whole pelvic radiotherapy (WPRT)), combined with long-term ADT can reach excellent prostate cancer specific survival (PCSS) in this population with little detrimental impact on quality of life.

METHODS

We searched Pubmed database until February 8, 2024. Studies reporting both oncological and toxicity outcomes after "augmented RT" were deemed eligible. Studies without ADT or with ARPI intensification were deemed ineligible.

RESULTS

Dose-escalation within the prostate gland at doses over 78 Gy halved the risk of biochemical recurrence at 5 years, with however no impact on PCSS. The addition of WPRT provides a 5-year disease-free survival (DFS) reaching 89.5 % at 5 years, with no significant increase in late grade≥ 2 genito-urinary (GU) or gastrointestinal (GI) toxicity. Combined approaches result in 9-year PCSS ranging between 96.1 % and 100 %. Most approaches demonstrated excellent safety profiles.

CONCLUSIONS

"Augmented RT" reached excellent oncological outcomes, with minimal additional toxicity. The development of biomarkers might lead to further treatment personalization, in the rapidly evolving landscape of systemic therapies.

Salvage radiotherapy with volumetric modulated arc therapy (VMAT) for recurrent prostate cancer after high-intensity focused ultrasound (HIFU): A large French retrospective series and literature review

BACKGROUND AND PURPOSE

Although not validated as a standard treatment, high-intensity focused ultrasound (HIFU) is increasingly used in the management of localised prostate cancer (PCa). In case of recurrence after HIFU, treatment is currently not standardised. Our aim was to evaluate normofractionated (NFRT) and hypofractionated (HFRT) salvage radiotherapy (RT) using volumetric modulated arc therapy (s-VMAT) with doses used in first-line management of localised PCa.

MATERIAL AND METHODS

We identified all patients with local or locoregional recurrence after HIFU treated with s-VMAT in 3 RT centres between 2014 and 2023. We evaluated acute and late toxicity and oncological outcomes.

RESULTS

Fifty-six patients were identified. Median age at recurrence was 75 (70-80) years. Median time between HIFU and s-VMAT was 26.5 months (13.9-47.2). S-VMAT was delivered to the prostate only in 35 (62.5 %) patients and to the prostate and pelvis in 21 (37.5 %) patients. NFRT and HFRT were delivered in 46 (82.1 %) and 10 (17.9 %) patients, respectively. Androgen deprivation therapy (ADT) was given to 27 (48.2 %) patients. Eighteen (32 %) and four (7 %) patients reported an acute grade 2 genitourinary (GU) and gastrointestinal (GI) adverse event (AE), respectively. Two patients presented with a late grade 2 GU AE, and one with a late grade 2 GI AE. No grade 3+ toxicity was reported. With a median follow-up of 19.5 months (12 - 47), no patient had a biochemical, local or distant relapse.

CONCLUSIONS

This is the largest series of salvage RT after HIFU using VMAT and escalated doses (78-80 Gy/39-40Fr., or 60 Gy/20Fr.). Acute toxicity was acceptable and late AEs were few. Longer follow-up is required to assess efficacy. Overall, available series suggest that salvage RT could represent a valuable option in the treatment of relapses after HIFU.

The Determinants of Toxicity in the Treatment of Prostate Cancer With a Focal, Intraprostatic "Microboost"

PURPOSE

A single-phase 3 trial has demonstrated that prostate radiation therapy with a focal, intraprostatic "microboost" can improve disease control without an overall increase in toxicity. It is unclear how these results generalize to other treatment schedules and protocols.

METHODS AND MATERIALS

A systematic search of PubMed and the Cochrane review was performed for studies published on or before September 1, 2023. A random-effects meta-analysis was used to pool the cumulative incidence of grade ≥2 (≥G2) acute and late genitourinary (GU) and gastrointestinal (GI) toxicity. Heterogeneity was assessed, and the association of trial-level covariates with toxicity was examined via the subgroup analyses and meta-regression. Odds ratios (ORs) for dose metrics were reported per Gy equivalent dose in 2Gy per fraction (EQD2).

RESULTS

Thirty-eight patient cohorts were included. The pooled estimate of the cumulative incidence of ≥G2 acute and late GU toxicity was 25.3% (95% CI, 19.1%-32.8%) and 21.1% (95% CI, 16.7%-26.3%), respectively. Late ≥G2 GI toxicity was less frequent, estimated at 5.6% (95% CI, 3.5%-8.7%) and 6.9% (95% CI, 4.6%-10.1%), respectively. Subgroup factors associated with at least one ≥G2 toxicity category were treatment technique, imaging used for boost volume definition, intrafraction motion management, trial phase, and toxicity grading. Rectal DMax was associated with acute ≥G2 GI toxicity (OR, 1.05; 95% CI, 1.02-1.08; P < .001). Additionally, urethral DMax was associated with late ≥G2 GU toxicity (OR, 1.02; 95% CI, 1.01-1.03; P < .001), and a stronger relationship was observed with the average plan urethral DMax (OR, 1.05; 95% CI, 1.03-1.07; P < .001). No association of toxicity with any bladder dose metric examined was observed.

CONCLUSIONS

The utilization of a microboost seems tolerable across treatment protocols; however, subgroup factors, including the use of intrafraction motion management and the type of imaging modality used, may influence the probability of toxicity. Attention to rectal DMax constraints and urethral DMax dose constraints may help to mitigate GI and GU toxicity, respectively. No association between toxicity and bladder dose constraints was observed.

Hypofractionated image-guided radiotherapy with 70 Gy in 28 fractions for prostate cancer confined to the pelvis: a single institute experience in Taiwan

BACKGROUND

The incidence of prostate cancer is increasing in Asian countries. Although moderately hypofractionated radiotherapy is not inferior to conventional fractionated radiation according to the updated guidelines, data regarding its efficacy and safety in Taiwan are currently lacking. The aim of this study was to investigate the outcomes of prostate cancer patients treated with hypofractionated image-guided radiotherapy at a single institution in Taiwan.

METHODS

We retrospectively included patients with prostate cancer across all risk groups who were treated with hypofractionated image-guided radiotherapy 70 Gy (Gy) in 28 fractions (at 2.5 Gy/fraction) between 2007 and 2022. We analyzed treatment efficacy by assessing overall survival, prostate cancer-specific survival, event-free survival, biochemical failure, locoregional recurrence, and distant metastasis. The safety of the treatment was evaluated through acute and late gastrointestinal (GI) and genitourinary (GU) toxicity grading based on the Radiation Therapy Oncology Group criteria. Event-free survival, overall survival, prostate cancer-specific survival, biochemical failure, locoregional recurrence, and distant metastasis were evaluated using the Kaplan-Meier method.

RESULTS

We identified 150 consecutive men with prostate cancer: 12.7% were at low risk, 32.7% were at intermediate risk, 44.6% were at high risk, and 10% had N1 disease. The median follow-up time was 68.9 months (range: 2.3-172 months). The 5-year overall survival rate was 91.7% for the entire cohort, with rates of 100%, 94.3%, 93.3% and 71.1% for the low-risk, intermediate-risk, high-risk, and N1-disease groups, respectively (p < 0.001). The 5-year event-free survival rate for all patients was 75.8%. Among the risk groups, the 5-year event-free survival rates were 100%, 86.3%, 68.3% and 52.5% for the low-risk, intermediate-risk, high-risk, and N1 disease groups, respectively (p < 0.001). Grade ≥ 2 late GI toxicity was rare (0.7%), and grade ≥ 2 late GU toxicity was observed in 9.3% of the patients.

CONCLUSIONS

Hypofractionated image-guided radiotherapy, delivering 70 Gy at 2.5 Gy per fraction, is both effective and safe for Taiwanese patients with prostate cancer across all risk groups, consistent with findings from existing large randomized trials. Therefore, as a solution to enhance patient convenience, hypofractionated radiotherapy is a reasonable option for the definitive treatment of prostate cancer.

TRIAL REGISTRATION

Not applicable.

Microboost in Localized Prostate Cancer: Analysis of a Statewide Quality Consortium

Purpose

Prospective trials have reported isotoxicity and improved oncologic outcomes with external beam radiation therapy (EBRT) microboost to a dominant intraprostatic lesion. There is often variability in the rate of adoption of new treatments, and current microboost practice patterns are unknown. We leveraged prospectively collected data from the multicenter Michigan Radiation Oncology Quality Consortium to understand the current state of microboost usage for localized prostate cancer.

Materials and Methods

Men with intermediate- and high-risk prostate adenocarcinoma treated with curative-intent radiation between October, 26, 2020, and June, 26, 2023, were included across 26 centers. Demographic-, tumor-, and treatment-related data along with DICOM files were prospectively collected. Microboost intent was prospectively documented and DICOM-confirmed. Multivariable analyses were used to evaluate associations with microboost receipt, and mixed-effects modeling evaluated facility-level variation.

Results

Most patients received EBRT without brachytherapy (71%, n = 524/741). Of those, a minority received an EBRT microboost (10%, n = 53/524) at a subset of sites (27%, n = 7/26), without a change in rate over the study period (P = .62). Grade group 4/5 (odds ration [OR] = 2.35; 95% confidence interval [CI]: 1.02-5.28), magnetic resonance imaging planning (OR = 6.34; 95%CI: 2.16-27.12), and fiducial marker/rectal spacer placement (OR = 2.59; 95% CI: 1.14-6.70) were associated with microboost use. Significant facility-level variability was present (minimum 0%; 95% CI: 0.0-10.7 to maximum 71%; 95% CI: 55.5-83.2, unadjusted, P < .0001). Median boost volume was 20.7cc, and median boost D98% was 94.4 EQD2Gy. Compared with non-microboost cases, intermediate doses to rectum in the microboost cohort were increased (eg, V20Gy [EQD2] of 53.8% vs 36.5%, P = .03). However, the proportion exceeding NRG/RTOG bladder/rectal constraints was low and not significantly different between cohorts.

Conclusions

Despite prospective data demonstrating its benefit, EBRT microboost was used within a diverse statewide quality consortium in only 10% of cases at 27% of sites with significant facility-level heterogeneity. Concerted efforts are required to understand current barriers to microboost utilization, and results from trials such as PIVOTALboost (ISRCTN80146950) are eagerly awaited.

Target Volume Optimization for Localized Prostate Cancer

PURPOSE

To provide a comprehensive review of the means by which to optimize target volume definition for the purposes of treatment planning for patients with intact prostate cancer with a specific emphasis on focal boost volume definition.

METHODS

Here we conduct a narrative review of the available literature summarizing the current state of knowledge on optimizing target volume definition for the treatment of localized prostate cancer.

RESULTS

Historically, the treatment of prostate cancer included a uniform prescription dose administered to the entire prostate with or without coverage of all or part of the seminal vesicles. The development of prostate magnetic resonance imaging (MRI) and positron emission tomography (PET) using prostate-specific radiotracers has ushered in an era in which radiation oncologists are able to localize and focally dose-escalate high-risk volumes in the prostate gland. Recent phase 3 data has demonstrated that incorporating focal dose escalation to high-risk subvolumes of the prostate improves biochemical control without significantly increasing toxicity. Still, several fundamental questions remain regarding the optimal target volume definition and prescription strategy to implement this technique. Given the remaining uncertainty, a knowledge of the pathological correlates of radiographic findings and the anatomic patterns of tumor spread may help inform clinical judgement for the definition of clinical target volumes.

CONCLUSION

Advanced imaging has the ability to improve outcomes for patients with prostate cancer in multiple ways, including by enabling focal dose escalation to high-risk subvolumes. However, many questions remain regarding the optimal target volume definition and prescription strategy to implement this practice, and key knowledge gaps remain. A detailed understanding of the pathological correlates of radiographic findings and the patterns of local tumor spread may help inform clinical judgement for target volume definition given the current state of uncertainty.

Proton therapy toxicity outcomes for localized prostate cancer: Long-term results at a comprehensive cancer center

Background

Proton therapy (PT) has unique biologic properties with excellent clinical outcomes for the management of localized prostate cancer. Here, we aim to characterize the toxicity of PT for patients with localized prostate cancer and propose mitigation strategies using a large institutional database.

Methods

We reviewed medical records of 2772 patients with localized prostate cancer treated with definitive PT between May 2006 through January 2020. Disease risk was stratified according to National Comprehensive Cancer Network guidelines as low [LR, n = 640]; favorable-intermediate [F-IR, n = 849]; unfavorable-intermediate [U-IR, n = 851]; high [HR, n = 315]; or very high [VHR, n = 117]. Descriptive statistics and Kaplan-Meier estimates assessed toxicity and freedom from biochemical relapse (FFBR).

Results

Median follow-up was 7.0 years. The median dose was 78 Gy(RBE)(range: 72-79.2 Gy) in 2.0 Gy(RBE) fractions; 63 % of patients received 78 Gy(RBE) in 39 fractions, and 29 % received 76 Gy(RBE) in 38 fractions. Overall rates of late grade ≥3 GU and GI toxicity were 0.87 % and 1.01 %, respectively. Two patients developed grade 4 late GU toxicity and seven patients with grade 4 late GI toxicity. All patients experiencing severe late grade 4 toxicities were treated to 78 Gy(RBE) in 39 fractions with 80 Gy(RBE) dose to the anterior rectal wall and/or bladder neck. The 10-year FFBR rates for patients with LR to U-IR disease were compared between those treated with 76 and 78 Gy(RBE); the rates were 94.5 % (95 % confidence interval [CI] 92.4-96.0 %) and 93.2 % (95 % CI 91.3-95.7 %), respectively (log-rank p = 0.22).

Conclusions

Proton therapy is associated with low rates of late grade ≥3 GU and GI toxicity. While rare, late grade 4 toxicities occurred in nine (0.3 %) patients. De-escalation to a total dose of 76 Gy(RBE) yields excellent clinical outcomes for patients with LR to U-IR disease with the potential for significant reductions in grade ≥3 late toxicity.

Clinical implementation of real time motion management for prostate SBRT: A radiation therapist's perspective

Background and purpose

The adoption of hypo-fractionated stereotactic body radiotherapy (SBRT) for treating prostate cancer has led to an increase in specialised techniques for monitoring prostate motion. The aim of this study was to comprehensively review a radiation therapist (RTT) led treatment process in which two such systems were utilised, and present initial findings on their use within a SBRT prostate clinical trial.

Materials and Methods

18 patients were investigated, nine were fitted with the Micropos RayPilotTM (RP) system (Micropos Medical, Gothenburg, SE) and nine were fitted with the Micropos Raypilot Hypocath TM (HC) system. 36.25 Gray (Gy) was delivered in 5 fractions over 7 days with daily pre- and post-treatment cone beam computed tomography (CBCT) images acquired. Acute toxicity was reported on completion of treatment at six- and 12-weeks post-treatment, using the Radiation Therapy Oncology Group (RTOG) grading system and vertical (Vrt), longitudinal (Lng) and lateral (Lat) transmitter displacements recorded.

Results

A significant difference was found in the Lat displacement between devices (P=0.003). A more consistent bladder volume was reported in the HC group (68.03 cc to 483.7 cc RP, 196.11 cc to 313.85 cc HC). No significant difference was observed in mean dose to the bladder, rectum and bladder dose maximum between the groups. Comparison of the rectal dose maximum between the groups reported a significant result (P=0.09). Comparing displacements with toxicity endpoints identified two significant correlations: Grade 2 Genitourinary (GU) at 6 weeks, P=0.029; and no toxicity, Gastrointestinal (GI) at 12 weeks P=0.013.

Conclusion

Both the directly implanted RP device and the urinary catheter-based HC device are capable of real time motion monitoring. Here, the HC system was advantageous in the SBRT prostate workflow.

EAU-EANM-ESTRO-ESUR-ISUP-SIOG Guidelines on Prostate Cancer-2024 Update. Part I: Screening, Diagnosis, and Local Treatment with Curative Intent

BACKGROUND AND OBJECTIVE

The European Association of Urology (EAU)-European Association of Nuclear Medicine (EANM)-European Society for Radiotherapy and Oncology (ESTRO)-European Society of Urogenital Radiology (ESUR)-International Society of Urological Pathology (ISUP)-International Society of Geriatric Oncology (SIOG) guidelines provide recommendations for the management of clinically localised prostate cancer (PCa). This paper aims to present a summary of the 2024 version of the EAU-EANM-ESTRO-ESUR-ISUP-SIOG guidelines on the screening, diagnosis, and treatment of clinically localised PCa.

METHODS

The panel performed a literature review of all new data published in English, covering the time frame between May 2020 and 2023. The guidelines were updated, and a strength rating for each recommendation was added based on a systematic review of the evidence.

KEY FINDINGS AND LIMITATIONS

A risk-adapted strategy for identifying men who may develop PCa is advised, generally commencing at 50 yr of age and based on individualised life expectancy. The use of multiparametric magnetic resonance imaging in order to avoid unnecessary biopsies is recommended. When a biopsy is considered, a combination of targeted and regional biopsies should be performed. Prostate-specific membrane antigen positron emission tomography imaging is the most sensitive technique for identifying metastatic spread. Active surveillance is the appropriate management for men with low-risk PCa, as well as for selected favourable intermediate-risk patients with International Society of Urological Pathology grade group 2 lesions. Local therapies are addressed, as well as the management of persistent prostate-specific antigen after surgery. A recommendation to consider hypofractionation in intermediate-risk patients is provided. Patients with cN1 PCa should be offered a local treatment combined with long-term intensified hormonal treatment.

CONCLUSIONS AND CLINICAL IMPLICATIONS

The evidence in the field of diagnosis, staging, and treatment of localised PCa is evolving rapidly. These PCa guidelines reflect the multidisciplinary nature of PCa management.

PATIENT SUMMARY

This article is the summary of the guidelines for "curable" prostate cancer. Prostate cancer is "found" through a multistep risk-based screening process. The objective is to find as many men as possible with a curable cancer. Prostate cancer is curable if it resides in the prostate; it is then classified into low-, intermediary-, and high-risk localised and locally advanced prostate cancer. These risk classes are the basis of the treatments. Low-risk prostate cancer is treated with "active surveillance", a treatment with excellent prognosis. For low-intermediary-risk active surveillance should also be discussed as an option. In other cases, active treatments, surgery, or radiation treatment should be discussed along with the potential side effects to allow shared decision-making.

Overall survival benefit of androgen suppression in addition to dose-escalated external beam radiotherapy for high-risk prostate cancer: Nationwide real-world data indicates a shift in men that benefit

OBJECTIVE

To evaluate the real-world added value of androgen deprivation therapy (ADT) in addition to external beam radiotherapy (EBRT) in men with high-risk non-metastatic prostate cancer, in view of advances in radiotherapy and diagnostics.

METHODS

All Dutch men diagnosed with high-risk non-metastatic prostate cancer (defined as: ≥cT2c-T3b N0M0, PSA ≥20-50 ng/ml, and/or Gleason score ≥8 (International Society of Urological Pathology [ISUP] grade ≥4)) from 2009 through 2019 and treated with EBRT with or without ADT were identified in the population-based Netherlands Cancer Registry. Propensity scores were used to match (1:1) men that received ADT to men that did not receive ADT. Subsequently, OS was compared. Analyses were also stratified by number of high-risk features, 1 (either ≥cT2c, PSA >20 ng/ml or Gleason score ≥8) versus ≥2 (out of ≥cT2c, PSA >20 ng/ml and Gleason score ≥8).

RESULTS

A total of 14,773 men with high-risk non-metastatic prostate cancer were identified, 3,958 (27%) of which received EBRT alone. After matching, 3,427 men remained in both groups and baseline characteristics were well-balanced. After a median follow-up of 92 months, OS was better in men treated with EBRT and ADT compared to men treated with EBRT alone (10-year OS: 66.4% versus 61.8%; HR 0.88 [95%CI: 0.80-0.96]). There was no statistically significant difference in OS in the subgroup of men with only 1 high-risk feature (10-year OS 67.7% versus 64.9%; HR 0.95 [95%CI: 0.85-1.07]).

CONCLUSIONS

In a contemporary cohort of men treated for high-risk non-metastatic prostate cancer with EBRT, an OS benefit of adding ADT was only observed in men with at least 2 high-risk features. These results suggest that improvements in diagnostics and treatment in recent decades have resulted in a stage shift of men benefiting from the addition of ADT to EBRT.

The effect of dose-escalation radiotherapy with simultaneous-integrated-boost on the use of short-term androgen deprivation therapy in patients with intermediate risk prostate cancer

PURPOSE

To compare the biochemical failure (FFBF) and prostate cancer specific survival (PCSS) rates of patients with intermediate-risk prostate cancer (IR-PC) who were treated with 6 months of androgen deprivation therapy (ADT) with 78 Gy to the prostate, those treated with ADT and focal boost (FB) of 86 Gy to intraprostatic lesion (IPL) using the simultaneous-integrated boost (SIB) technique, and those treated with SIB alone.

MATERIALS AND METHODS

A retrospective analysis of 320 IR-PC patients treated between January 2012 and April 2021 was performed. Patients were divided into three groups based on their treatment arm: 78 + ADT (109 patients, 34.1%), 78/86 (102 patients, 31.8%), and 78/86 + ADT. Univariable and multivariable analyses were used to determine prognostic factors for FFBF and PCSS.

RESULTS

Median follow-up was 8.8 years. The 8-year FFBF and PCSS rates were 88.6% and 99.0%. Patients who received ADT had significantly higher pretreatment PSA levels and clinical tumor stage. Disease progression occurred in 45 patients (7.3%) at a median of 41.9 months after definitive radiotherapy (RT). Younger age, positive core biopsy (PCB) ≥ 50%, and the absence of ADT were all independent predictors of poor FFBF in multivariate analysis, whereas patients with PCB < 50% who were also given ADT had better PCSS. Patients treated with 78/86 Gy alone had worse FFBF than those treated with 78 Gy and ADT (Hazard ratio [HR] = 3.39 [95% CI = 1.46-7.88]; p = 0.005), as well as than those treated with 78/86 Gy and ADT (HR = 3.21 [95% CI = 1.23-6.46]; p = 0.009). However, FB to IPL has no effect on PCSS in multivariable analysis. There was no significant difference between treatment groups in terms of acute and late Grade ≥2 genitourinary or gastrointestinal toxicity.

CONCLUSIONS

Our findings demonstrated that patients who received 78/86 alone did worse than patients who received ADT with either 78 or 78/86 Gy. However, because IR-PC patients are so diverse, additional prospective trials are needed to validate our findings.

Towards optimal heterogeneous prostate radiotherapy dose prescriptions based on patient-specific or population-based biological features

BACKGROUND

Escalation of prescribed dose in prostate cancer (PCa) radiotherapy enables improvement in tumor control at the expense of increased toxicity. Opportunities for reduction of treatment toxicity may emerge if more efficient dose escalation can be achieved by redistributing the prescribed dose distribution according to the known heterogeneous, spatially-varying characteristics of the disease.

PURPOSE

To examine the potential benefits, limitations and characteristics of heterogeneous boost dose redistribution in PCa radiotherapy based on patient-specific and population-based spatial maps of tumor biological features.

METHOD

High-resolution prostate histology images, from a cohort of 63 patients, annotated with tumor location and grade, provided patient-specific "maps" and a population-based "atlas" of cell density and tumor probability. Dose prescriptions were derived for each patient based on a heterogeneous redistribution of the boost dose to the intraprostatic lesions, with the prescription maximizing patient tumor control probability (TCP). The impact on TCP was assessed under scenarios where the distribution of population-based biological data was ignored, partially included, or fully included in prescription generation. Heterogeneous dose prescriptions were generated for three combinations of maps and atlas, and for conventional fractionation (CF), extreme hypo-fractionation (EH), moderate hypo-fractionation (MH), and whole Pelvic RT + SBRT Boost (WPRT + SBRT). The predicted efficacy of the heterogeneous prescriptions was compared with equivalent homogeneous dose prescriptions.

RESULTS

TCPs for heterogeneous dose prescriptions were generally higher than those for homogeneous dose prescriptions. TCP escalation by heterogeneous dose prescription was the largest for CF. When only using population-based atlas data, the generated heterogeneous dose prescriptions of 55 to 58 patients (out of 63) had a higher TCP than for the corresponding homogeneous dose prescriptions. The TCPs of the heterogeneous dose prescriptions generated with the population-based atlas and tumor probability maps did not differ significantly from those using patient-specific biological information. The generated heterogeneous dose prescriptions achieved significantly higher TCP than homogeneous dose prescriptions in the posterior section of the prostate.

CONCLUSION

Heterogeneous dose prescriptions generated via biologically-optimized dose redistribution can produce higher TCP than the homogeneous dose prescriptions for the majority of the patients in the studied cohort. For scenarios where patient-specific biological information was unavailable or partially available, the generated heterogeneous dose prescriptions can still achieve TCP improvement relative to homogeneous dose prescriptions.

In Curative Stereotactic Body Radiation Therapy for Prostate Cancer, There Is a High Possibility That 45 Gy in Five Fractions Will Not Be Tolerated without a Hydrogel Spacer

The purpose of this study was to determine the maximum tolerated dose (MTD) for stereotactic body radiation therapy (SBRT) in the treatment of non-metastatic prostate cancer. This study was a phase 1 dose escalation trial conducted in Japan. Patients with histologically proven prostate cancer without lymph nodes or distant metastases were enrolled. The prescribed doses were 42.5, 45, or 47.5 Gy in five fractions. Dose-limiting toxicity (DLT) was defined as grade (G) 3+ gastrointestinal or genitourinary toxicity within 180 days after SBRT completion, and a 6 plus 6 design was used as the method of dose escalation. A total of 16 patients were enrolled, with 6 in the 42.5 Gy group and 10 in the 45 Gy group. No DLT was observed in the 42.5 Gy group. In the 45 Gy group, one patient experienced G3 rectal hemorrhage, and another had G4 rectal perforation, leading to the determination of 42.5 Gy as the MTD. None of the patients experienced biochemical recurrence or death during the follow-up period. We concluded that SBRT for non-metastatic prostate cancer at 42.5 Gy in five fractions could be safely performed, but a total dose of 45 Gy increased severe toxicity.

Rectal deformation management with IGRT in prostate radiotherapy: Can it be managed with rigid alignment alone?

PURPOSE

It is challenging to achieve appropriate target coverage of the prostate with Image Guided Radiation Therapy (IGRT) while simultaneously constraining rectal doses within planned values when there is significant variability in rectal filling and shape. We investigated if rectum planning goals can be fulfilled using rigid CBCT-based on-board alignment to account for interfraction rectal deformations.

METHODS

Delivered rectal doses corresponding to prostate alignment ("PR") and anterior rectum alignment ("AR") for 239 daily treatments from 13 patients are reported. Rectal doses were estimated by rigidly mapping the planned dose on the daily CT derived from the daily CBCT according to respective alignment shifts. Rectum V95% (rV95%) was used for analyses.

RESULTS

Compared to "PR", "AR" alignment increased rV95% for an average of 34.4% across all patients. rV95% (cc) averaged over all fractions was significant from planning values for 10/13 patients for "PR" and for 9/13 for "AR". 3/13 patients had reproducible anatomy. Of patients with non-reproducible anatomy, three had dosimetrically more favorable, while seven had less favorable anatomies. Most shift differences (82.3%) between the "PR" and "AR" alignments larger than 2 mm resulted in rV95% changes larger than 2 cc. Most shift differences (82.2%) of 2 mm or less between the "PR" and "AR" alignments resulted in rV95% changes less than 2 cc. The average percentage of fractions among patients in which anterior or posterior shifts for "AR" and "PR" alignment was larger than the PTV margins was 9.1% (0.0%-37.5%) and 1.3% (0%-10%).

CONCLUSION

Rectal deformation and subsequent inconsistent interfraction separation between prostate and rectal wall translate into anatomical changes that cannot always be mitigated with rigid alignment. If systematic differences exist due to a non-reproducible planning anatomy, attempts to restore the planned rectal doses through anterior rectum alignment produce rather small improvements and may result in unacceptable target underdosage.

Trimodality Therapy With Iodine-125 Brachytherapy, External Beam Radiation Therapy, and Short- or Long-Term Androgen Deprivation Therapy for High-Risk Localized Prostate Cancer: Results of a Multicenter, Randomized Phase 3 Trial (TRIP/TRIGU0907)

PURPOSE

This phase 3 randomized investigation was designed to determine whether 30 months of androgen deprivation therapy (ADT) was superior to 6 months of ADT when combined with brachytherapy and external beam radiation therapy (EBRT) for localized high-risk prostate cancer.

METHODS AND MATERIALS

This study was conducted at 37 hospitals on men aged 40 to 79 years, with stage T2c-3a, prostate-specific antigen >20 ng/mL, or Gleason score >7, who received 6 months of ADT combined with iodine-125 brachytherapy followed by EBRT. After stratification, patients were randomly assigned to either no further treatment (short arm) or 24 months of adjuvant ADT (long arm). According to the Phoenix definition of failure, the primary endpoint was the cumulative incidence of biochemical progression. Secondary endpoints included clinical progression, metastasis, salvage treatment, disease-specific mortality, overall survival, and grade 3+ adverse events. An intention-to-treat analysis was conducted using survival estimates determined using competing risk analyses.

RESULTS

Of 332 patients, 165 and 167 were randomly assigned to the short and long arms, respectively. The median follow-up period was 9.2 years. The cumulative incidence of biochemical progression at 7 years was 9.0% (95% CI, 5.5-14.5) and 8.0% (4.7-13.5) in the short and long arms, respectively (P = .65). The outcomes of secondary endpoints did not differ significantly between the arms. Incidence rates of endocrine- and radiation-related grade 3+ adverse events for the short versus long arms were 0.6 versus 1.8% (P = .62) and 1.2 versus 0.6% (P = .62), respectively.

CONCLUSIONS

Both treatment arms showed similar efficacy among selected populations with high-risk features. The toxicity of the trimodal therapy was acceptable. The present investigation, designed as a superiority trial, failed to demonstrate that 30-month ADT yielded better biochemical control than 6-month ADT when combined with brachytherapy and EBRT. Therefore, a noninferiority study is warranted to obtain further evidence supporting these preliminary results.

Approach to Patients with High-Risk Localized Prostate Cancer: Radiation Oncology Perspective

OPINION STATEMENT

High-risk localized prostate cancer is a challenging clinical entity to treat, with heterogeneous responses to an evolving array of multidisciplinary treatment approaches. In addition, this disease state is growing in incidence due to a variety of factors, including shifting recommendations that discouraged routine prostate cancer screening. Current guidelines now incorporate an informed decision-making process for prostate cancer screening and evaluation. More work is underway to improve targeted screening for certain at-risk populations and to implement greater personalization in the use of diagnostic tools. Once diagnosed with high-risk localized disease, a multimodality treatment paradigm is warranted. Radiation-in its various forms and combinations-plays a large and continually evolving role in the management of high-risk prostate cancer, yet treatment outcomes are still suboptimal. There is a growing need to improve upon current treatment approaches, and better personalize a particular treatment recommendation based on both tumor and patient characteristics, as well as patient preference and goals of therapy. Given that treatment generally requires more than one therapy, there are notable implications on long-term quality of life, especially with respect to overlapping and cumulative side effects of local and systemic therapies, respectively. The desire for aggressive therapy to optimize cancer control outcomes must be weighed against the risk of morbidities and overtreatment and discussed with each patient so that an informed decision about treatment and care can be determined. High-level evidence to support treatment recommendations, where available, is critical for a data-driven and tailored approach to address all goals of care.

Long-term Overall Survival after External Beam Radiotherapy for Localised Prostate Cancer

AIMS

Knowledge on survival probabilities is essential for determining optimal treatment strategies. We studied overall survival and associated prognostic factors in Dutch patients with localised prostate cancer (PCa) selected for external beam radiotherapy.

MATERIALS AND METHODS

For this single-centre retrospective cohort study, we identified all T1-T3 PCa patients (aged 55-80 years) in the radiotherapy planning database with a start date between January 2006 and December 2013, treated with 72-78 Gy in 2 Gy fractions to the prostate ± seminal vesicles (n = 1536). Long-term androgen deprivation therapy (ADT) was predominantly prescribed in the case of extracapsular disease (>T3). Overall survival was estimated using the Kaplan-Meier method. Prognostic factors were evaluated in Cox regression models for the intermediate-risk and high-risk groups.

RESULTS

The median follow-up was 12 years for patients who were alive. Ten-year survival rates were 79.0% for low-risk (n = 120), 59.9% for intermediate-risk (n = 430) and 56.8% for high-risk patients (n = 986). A higher age, higher comorbidity score, active smoking and Gleason score ≥8 had a statistically significant negative impact on overall survival at multivariable analysis. ADT was associated with superior overall survival in the high-risk group translating into overall survival rates similar to the intermediate-risk group.

CONCLUSIONS

Although PCa patients selected for external beam radiotherapy are typically in good health, their comorbidity score and smoking habits appeared to be dominant predictors for overall survival. Overall survival rates within the high-risk group varied, showing improved overall survival with ADT prescription and worse overall survival in the case of Gleason score ≥8.

Proton therapy for the management of localized prostate cancer: Long-term clinical outcomes at a comprehensive cancer center

BACKGROUND AND PURPOSE

Proton therapy (PT) has emerged as a standard-of-care treatment option for localized prostate cancer at our comprehensive cancer center. However, there are few large-scale analyses examining the long-term clinical outcomes. Therefore, this article aims to evaluate the long-term effectiveness and toxicity of PT in patients with localized prostate cancer.

MATERIALS AND METHODS

Review of 2772 patients treated from May 2006 through January 2020. Disease risk was stratified according to National Comprehensive Cancer Network guidelines as low [LR, n = 640]; favorable-intermediate [F-IR, n = 850]; unfavorable-intermediate [U-IR, n = 851]; high [HR, n = 315]; or very high [VHR, n = 116]. Biochemical failure and toxicity were analyzed using Kaplan-Meier estimates and multivariate models.

RESULTS

The median patient age was 66 years; the median follow-up time was 7.0 years. Pelvic lymph node irradiation was prescribed to 28 patients (1%) (2 [0.2%] U-IR, 11 [3.5%] HR, and 15 [12.9%] VHR). The median dose was 78 Gy in 1.8-2.0 Gy(RBE) fractions. Freedom from biochemical relapse (FFBR) rates at 5 years and 10 years were 98.2% and 96.8% for the LR group; 98.3% and 93.6%, F-IR; 94.2% and 90.2%, U-IR; 94.3% and 85.2%, HR; and 86.1% and 68.5%, VHR. Two patients died of prostate cancer. Overall rates of late grade ≥ 3 GU and GI toxicity were 0.87% and 1.01%.

CONCLUSIONS

Proton therapy for localized prostate cancer demonstrated excellent clinical outcomes in this large cohort, even among higher-risk groups with historically poor outcomes despite aggressive therapy.

Dose evaluation of inter- and intra-fraction prostate motion in extremely hypofractionated intensity-modulated proton therapy for prostate cancer

Inter- and intra-fractional prostate motion can deteriorate the dose distribution in extremely hypofractionated intensity-modulated proton therapy. We used verification CTs and prostate motion data calculated from 1024 intra-fractional prostate motion records to develop a voxel-wise based 4-dimensional method, which had a time resolution of 1 s, to assess the dose impact of prostate motion. An example of 100 fractional simulations revealed that motion had minimal impact on planning dose, the accumulated dose in 95 % of the scenarios fulfilled the clinical goals for target coverage (D95 > 37.5 Gy). This method can serve as a complementary measure in clinical setting to guarantee plan quality.

Radical prostatectomy versus external beam radiotherapy with androgen deprivation therapy for high-risk prostate cancer: a systematic review

BACKGROUND

To summarize recent evidence in terms of health-related quality of life (HRQoL), functional and oncological outcomes following radical prostatectomy (RP) compared to external beam radiotherapy (EBRT) and androgen deprivation therapy (ADT) for high-risk prostate cancer (PCa).

METHODS

We searched Medline, Embase, Cochrane Database of Systematic Reviews, Cochrane Controlled Trial Register and the International Standard Randomized Controlled Trial Number registry on 29 march 2021. Comparative studies, published since 2016, that reported on treatment with RP versus dose-escalated EBRT and ADT for high-risk non-metastatic PCa were included. The Newcastle-Ottawa Scale was used to appraise quality and risk of bias. A qualitative synthesis was performed.

RESULTS

Nineteen studies, all non-randomized, met the inclusion criteria. Risk of bias assessment indicated low (n = 14) to moderate/high (n = 5) risk of bias. Only three studies reported functional outcomes and/or HRQoL using different measurement instruments and methods. A clinically meaningful difference in HRQoL was not observed. All studies reported oncological outcomes and survival was generally good (5-year survival rates > 90%). In the majority of studies, a statistically significant difference between both treatment groups was not observed, or only differences in biochemical recurrence-free survival were reported.

CONCLUSIONS

Evidence clearly demonstrating superiority in terms of oncological outcomes of either RP or EBRT combined with ADT is lacking. Studies reporting functional outcomes and HRQoL are very scarce and the magnitude of the effect of RP versus dose-escalated EBRT with ADT on HRQoL and functional outcomes remains largely unknown.

A pilot study of MRI radiomics for high-risk prostate cancer stratification in 1.5 T MR-guided radiotherapy

PURPOSE

To investigate the potential value of MRI radiomics obtained from a 1.5 T MRI-guided linear accelerator (MR-LINAC) for D'Amico high-risk prostate cancer (PC) classification in MR-guided radiotherapy (MRgRT).

METHODS

One hundred seventy-six consecutive PC patients underwent 1.5 T MRgRT treatment were retrospectively enrolled. Each patient received one or two pretreatment T₂ -weighted MRI scans on a 1.5 T MR-LINAC. The endpoint was to differentiate high-risk from low/intermediate-risk PC based on D'Amico criteria using MRI-radiomics. Totally 1023 features were extracted from clinical target volume (CTV) and planning target volume (PTV). Intraclass correlation coefficient of scan-rescan repeatability, feature correlation, and recursive feature elimination were used for feature dimension reduction. Least absolute shrinkage and selection operator regression was employed for model construction. Receiver operating characteristic area under the curve (AUC) analysis was used for model performance assessment in both training and testing data.

RESULTS

One hundred and eleven patients fulfilled all criteria were finally included: 76 for training and 35 for testing. The constructed MRI-radiomics models extracted from CTV and PTV achieved the AUC of 0.812 and 0.867 in the training data, without significant difference (P = 0.083). The model performances remained in the testing. The sensitivity, specificity, and accuracy were 85.71%, 64.29%, and 77.14% for the PTV-based model; and 71.43%, 71.43%, and 71.43% for the CTV-based model. The corresponding AUCs were 0.718 and 0.750 (P = 0.091) for CTV- and PTV-based models.

CONCLUSION

MRI-radiomics obtained from a 1.5 T MR-LINAC showed promising results in D'Amico high-risk PC stratification, potentially helpful for the future PC MRgRT. Prospective studies with larger sample sizes and external validation are warranted for further verification.

Toxicity of dose-escalated radiotherapy up to 84 Gy for prostate cancer

PURPOSE

The outcome of radiotherapy (RT) for prostate cancer (PCA) depends on the delivered dose. While the evidence for dose-escalated RT up to 80 gray (Gy) is well established, there have been only few studies examining dose escalation above 80 Gy. We initiated the present study to assess the safety of dose escalation up to 84 Gy.

METHODS

In our retrospective analysis, we included patients who received dose-escalated RT for PCA at our institution between 2016 and 2021. We evaluated acute genitourinary (GU) and gastrointestinal (GI) toxicity as well as late GU and GI toxicity.

RESULTS

A total of 86 patients could be evaluated, of whom 24 patients had received 80 Gy and 62 patients 84 Gy (35 without pelvic and 27 with pelvic radiotherapy). Regarding acute toxicities, no > grade 2 adverse events occurred. Acute GU/GI toxicity of grade 2 occurred in 12.5%/12.5% of patients treated with 80 Gy, in 25.7%/14.3% of patients treated with 84 Gy to the prostate only, and in 51.9%/12.9% of patients treated with 84 Gy and the pelvis included. Late GU/GI toxicity of grade ≥ 2 occurred in 4.2%/8.3% of patients treated with 80 Gy, in 7.1%/3.6% of patients treated with 84 Gy prostate only, and in 18.2%/0% of patients treated with 84 Gy pelvis included (log-rank test p = 0.358).

CONCLUSION

We demonstrated that dose-escalated RT for PCA up to 84 Gy is feasible and safe without a significant increase in acute toxicity. Further follow-up is needed to assess late toxicity and survival.

Dose-escalated radiotherapy for clinically localized and locally advanced prostate cancer

BACKGROUND

Treatments for clinically localized prostate cancer include radical prostatectomy, external beam radiation therapy, brachytherapy, active surveillance, hormonal therapy, and watchful waiting. For external beam radiation therapy, oncological outcomes may be expected to improve as the dose of radiotherapy (RT) increases. However, radiation-mediated side effects on surrounding critical organs may also increase.

OBJECTIVES

To assess the effects of dose-escalated RT in comparison with conventional dose RT for curative treatment of clinically localized and locally advanced prostate cancer.

SEARCH METHODS

We performed a comprehensive search using multiple databases including trial registries and other sources of grey literature, up until 20 July 2022. We applied no restrictions on publication language or status.

SELECTION CRITERIA

We included parallel-arm randomized controlled trials (RCTs) of definitive RT in men with clinically localized and locally advanced prostate adenocarcinoma. RT was dose-escalated RT (equivalent dose in 2 Gy [EQD2] ≥ 74 Gy, lesser than 2.5 Gy per fraction) versus conventional RT (EQD2 < 74 Gy, 1.8 Gy or 2.0 Gy per fraction). Two review authors independently classified studies for inclusion or exclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently abstracted data from the included studies. We performed statistical analyses by using a random-effects model and interpreted them according to the Cochrane Handbook for Systematic Reviews of Interventions. We used GRADE guidance to rate the certainty of the evidence of RCTs.

MAIN RESULTS

We included nine studies with 5437 men in an analysis comparing dose-escalated RT versus conventional dose RT for the treatment of prostate cancer. The mean participant age ranged from 67 to 71 years. Almost all men had localized prostate cancer (cT1-3N0M0). Primary outcomes Dose-escalated RT probably results in little to no difference in time to death from prostate cancer (hazard ratio [HR] 0.83, 95% CI 0.66 to 1.04; I2 = 0%; 8 studies; 5231 participants; moderate-certainty evidence). Assuming a risk of death from prostate cancer of 4 per 1000 at 10 years in the conventional dose RT group, this corresponds to 1 fewer men per 1000 (1 fewer to 0 more) dying of prostate cancer in the dose-escalated RT group. Dose-escalated RT probably results in little to no difference in severe RT toxicity of grade 3 or higher late gastrointestinal (GI) toxicity (RR 1.72, 95% CI 1.32 to 2.25; I2 = 0%; 8 studies; 4992 participants; moderate-certainty evidence); 23 more men per 1000 (10 more to 40 more) in the dose-escalated RT group assuming severe late GI toxicity as 32 per 1000 in the conventional dose RT group. Dose-escalated RT probably results in little to no difference in severe late genitourinary (GU) toxicity (RR 1.25, 95% CI 0.95 to 1.63; I2 = 0%; 8 studies; 4962 participants; moderate-certainty evidence); 9 more men per 1000 (2 fewer to 23 more) in the dose-escalated RT group assuming severe late GU toxicity as 37 per 1000 in the conventional dose RT group. Secondary outcomes Dose-escalated RT probably results in little to no difference in time to death from any cause (HR 0.98, 95% CI 0.89 to 1.09; I2 = 0%; 9 studies; 5437 participants; moderate-certainty evidence). Assuming a risk of death from any cause of 101 per 1000 at 10 years in the conventional dose RT group, this corresponds to 2 fewer men per 1000 (11 fewer to 9 more) in the dose-escalated RT group dying of any cause. Dose-escalated RT probably results in little to no difference in time to distant metastasis (HR 0.83, 95% CI 0.57 to 1.22; I2 = 45%; 7 studies; 3499 participants; moderate-certainty evidence). Assuming a risk of distant metastasis of 29 per 1000 in the conventional dose RT group at 10 years, this corresponds to 5 fewer men per 1000 (12 fewer to 6 more) in the dose-escalated RT group developing distant metastases. Dose-escalated RT may increase overall late GI toxicity (RR 1.27, 95% CI 1.04 to 1.55; I2 = 85%; 7 studies; 4328 participants; low-certainty evidence); 92 more men per 1000 (14 more to 188 more) in the dose-escalated RT group assuming overall late GI toxicity as 342 per 1000 in the conventional dose RT group. However, dose-escalated RT may result in little to no difference in overall late GU toxicity (RR 1.12, 95% CI 0.97 to 1.29; I2 = 51%; 7 studies; 4298 participants; low-certainty evidence); 34 more men per 1000 (9 fewer to 82 more) in the dose-escalated RT group assuming overall late GU toxicity as 283 per 1000 in the conventional dose RT group. Based on long-term follow-up (up to 36 months), dose-escalated RT may result or probably results in little to no difference in the quality of life using 36-Item Short Form Survey; physical health (MD -3.9, 95% CI -12.78 to 4.98; 1 study; 300 participants; moderate-certainty evidence) and mental health (MD -3.6, 95% CI -83.85 to 76.65; 1 study; 300 participants; low-certainty evidence), respectively.

AUTHORS' CONCLUSIONS

Compared to conventional dose RT, dose-escalated RT probably results in little to no difference in time to death from prostate cancer, time to death from any cause, time to distant metastasis, and RT toxicities (except overall late GI toxicity). While dose-escalated RT may increase overall late GI toxicity, it may result, or probably results, in little to no difference in physical and mental quality of life, respectively.

Long-term oncologic outcomes of low dose-rate brachytherapy compared to hypofractionated external beam radiotherapy for intermediate -risk prostate cancer

PURPOSE

To compare the long-term oncologic outcomes of intermediate risk (IR) prostate cancer (PCa) patients treated with low dose-rate brachytherapy (LDR-BT) or moderate hypofractionated external beam radiotherapy (HF-EBRT).

METHODS AND MATERIALS

Patients diagnosed with IR PCa and treated with LDR-BT or HF-EBRT between January 2005 and December 2013 were included. Brachytherapy treatment involved a transperineal implant of iodine-125 to a dose of 145 Gy to the PTV, while HF-EBRT was delivered using intensity modulated radiotherapy with 60 Gy in 20 fractions. The Phoenix ''nadir +2'' threshold was used to define biochemical relapse (BR). The cumulative incidence function (CIF) of BR and metastases was reported for each group and compared using the Gray's test to account for the competing risk of death. The Kaplan-Meier (KM) method was used to estimate overall survival (OS) and prostate cancer specific survival (PCSS). Univariate (UVA) and multivariable (MVA) analysis of the CIF of BR and metastases were performed. A 2-tailed p-value ≤ 0.05 was considered statistically significant.

RESULTS

Overall, 122 and 124 patients were treated with LDR-BT and HF-EBRT respectively. Median follow-up was 95 months [interquartile range (IQR): 79-118] in the LDR-BT group and 96 months (IQR: 63-123) in the HF-EBRT group. BR was observed in 5 patients treated with LDR-BT and 34 treated with HF-EBRT. At 60 and 90 months, the CIF of BR was 0.9% and 3.5% in the LDR-BT group vs. 16.6% and 23.7% in the HF-EBRT (p < 0.001). The CIF of metastases at 90 and 108 months, was 0% and 1.6% vs. 3.4% and 9.1% in the LDR-BT and HF-EBRT groups (p = 0.003), respectively. At the last follow-up, 3 patients treated with HF-EBRT died from their cancer [PCSS of 97.5% at 8 years and none died in the LDR-BT group (p = 0.09). On UVA and MVA risk group and treatment modality were independently associated with CIF of BR. On UVA HF-EBRT and ISUP grade group 3 were associated with metastases.

CONCLUSION

LDR-BT was associated with higher biochemical and metastases control in our cohort when compared to moderately HF-EBRT. In the absence of a randomized trial, LDR-BT when feasible should be offered to patients with a life expectancy of >8 years.

Is an Endorectal Balloon Beneficial for Rectal Sparing after Spacer Implantation in Prostate Cancer Patients Treated with Hypofractionated Intensity-Modulated Proton Beam Therapy? A Dosimetric and Radiobiological Comparison Study

BACKGROUND

The aim of this study is to examine the dosimetric influence of endorectal balloons (ERB) on rectal sparing in prostate cancer patients with implanted hydrogel rectum spacers treated with dose-escalated or hypofractionated intensity-modulated proton beam therapy (IMPT).

METHODS

Ten patients with localized prostate cancer included in the ProRegPros study and treated at our center were investigated. All patients underwent placement of hydrogel rectum spacers before planning. Two planning CTs (with and without 120 cm3 fluid-filled ERB) were applied for each patient. Dose prescription was set according to the h strategy, with 72 Gray (Gy)/2.4 Gy/5× weekly to prostate + 1 cm of the seminal vesicle, and 60 Gy/2 Gy/5× weekly to prostate + 2 cm of the seminal vesicle. Planning with two laterally opposed IMPT beams was performed in both CTs. Rectal dosimetry values including dose-volume statistics and normal tissue complication probability (NTCP) were compared for both plans (non-ERB plans vs. ERB plans).

RESULTS

For ERB plans compared with non-ERB, the reductions were 8.51 ± 5.25 Gy (RBE) (p = 0.000) and 15.76 ± 11.11 Gy (p = 0.001) for the mean and the median rectal doses, respectively. No significant reductions in rectal volumes were found after high dose levels. The use of ERB resulted in significant reduction in rectal volume after receiving 50 Gy (RBE), 40 Gy (RBE), 30 Gy (RBE), 20 Gy (RBE), and 10 Gy (RBE) with p values of 0.034, 0.008, 0.003, 0.001, and 0.001, respectively. No differences between ERB and non-ERB plans for the anterior rectum were observed. ERB reduced posterior rectal volumes in patients who received 30 Gy (RBE), 20 Gy (RBE), or 10 Gy (RBE), with p values of 0.019, 0.003, and 0.001, respectively. According to the NTCP models, no significant reductions were observed in mean or median rectal toxicity (late rectal bleeding ≥ 2, necrosis or stenosis, and late rectal toxicity ≥ 3) when using the ERB.

CONCLUSION

ERB reduced rectal volumes exposed to intermediate or low dose levels. However, no significant reduction in rectal volume was observed in patients receiving high or intermediate doses. There was no benefit and also no disadvantage associated with the use of ERB for late rectal toxicity, according to available NTCP models.

Functional imaging-guided carbon ion irradiation with simultaneous integrated boost for localized prostate cancer: study protocol for a phase II randomized controlled clinical trial

Background

Due to the physical dose distribution characteristic of “Bragg peak” and the biological effect as a kind of high linear energy transfer ray, heavy ion therapy has advantages over conventional photon therapy in both efficacy and safety. Based on the evidence that prostate cancer lesions before treatment are the most common sites of tumor residual or recurrence after treatment, simultaneous integrated boost radiation therapy for prostate cancer has been proven to have the advantage of improving efficacy without increasing toxicities.

Methods

This study is a prospective phase II randomized controlled clinical trial evaluating the efficacy and safety of functional imaging-guided carbon ion irradiation with simultaneous integrated boost for localized prostate cancer. One hundred and forty patients with localized prostate cancer will be randomized into carbon ion radiotherapy group and simultaneous integrated boost carbon ion radiotherapy group at a 1:1 ratio. The primary endpoint is to compare the incidence of treatment-related grade 2 and higher acute toxicities between the two groups according to National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE) version 4.03. Secondary endpoints are late toxicities, biochemical relapse-free survival, overall survival, progression-free survival, and quality of life.

Discussion

This study adopts functional imaging-guided simultaneous integrated boost of carbon ion radiotherapy for localized prostate cancer, aiming to evaluate the differences in the severity and incidence of acute toxicities in patients with localized prostate cancer treated with carbon ion radiotherapy and simultaneous integrated boost carbon ion radiotherapy, in order to optimize the carbon ion treatment strategy for localized prostate cancer.

Trial registration

ClinicalTrials.gov NCT05010343. Retrospectively registered on 18 August 2021

Dose-escalation in prostate cancer: Results of randomized trials

In 1998, an editorial from the International Journal of Radiation Oncology - Biology - Physics (IJROBP) on the occasion of the publication of Phase I by Zelefsky et al. on 3D radiotherapy dose escalation asked the question: "will more prove better?". More than 20 years later, several prospective studies have supported the authors' conclusions, making dose escalation a new standard in prostate cancer. The data from prospective randomized studies were ultimately disappointing in that they failed to show an overall survival benefit from dose escalation. However, there is a clear and consistent benefit in biochemical recurrence-free survival, which must be weighed on an individual patient basis against the potential additional toxicity of dose escalation. Techniques and concepts have become more and more precise, such as intensity modulated irradiation, simultaneous integrated boost, hypofractionated dose-escalation, pelvic irradiation with involved node boost or focal dose-escalation on gross recurrence after prostatectomy. The objective here was to summarize the prospective data on dose escalation in prostate cancer and in particular on recent advances in the field. In 2022, can we finally say that more has proven better?

Propensity score matching analysis comparing radical prostatectomy and radiotherapy with androgen deprivation therapy in locally advanced prostate cancer

To compare clinical outcomes between the use of robotic-assisted laparoscopic radical prostatectomy (RP) and radiotherapy (RT) with long-term androgen deprivation therapy (ADT) in locally advanced prostate cancer (PC), 315 patients with locally advanced PC (clinical T-stage 3/4) were considered for analysis retrospectively. Propensity score-matching at a 1:1 ratio was performed. The median follow-up period was 59.2 months (IQR 39.8–87.4). There were 117 (37.1%) patients in the RP group and 198 (62.9%) patients in the RT group. RT patients were older and had higher PSA at diagnosis, higher Gleason score grade group and more advanced T-stage (all p < 0.001). After propensity score-matching, there were 68 patients in each group. Among locally advanced PC patients, treatment with RP had a higher risk of biochemical recurrence compared to the RT group. In multivariate Cox regression analysis, treatment with RT plus ADT significantly decreased the risk of biochemical failure (HR 0.162, p < 0.001), but there was no significant difference in local recurrence, distant metastasis and overall survival (p = 0.470, p = 0.268 and p = 0.509, respectively). This information supported a clinical benefit in BCR control for patients undergoing RT plus long-term ADT compared to RP.

A Prospective Study of Stereotactic Body Radiotherapy (SBRT) with Concomitant Whole-Pelvic Radiotherapy (WPRT) for High-Risk Localized Prostate Cancer Patients Using 1.5 Tesla Magnetic Resonance Guidance: The Preliminary Clinical Outcome

Background: Conventionally fractionated whole-pelvic nodal radiotherapy (WPRT) improves clinical outcome compared to prostate-only RT in high-risk prostate cancer (HR-PC). MR-guided stereotactic body radiotherapy (MRgSBRT) with concomitant WPRT represents a novel radiotherapy (RT) paradigm for HR-PC, potentially improving online image guidance and clinical outcomes. This study aims to report the preliminary clinical experiences and treatment outcome of 1.5 Tesla adaptive MRgSBRT with concomitant WPRT in HR-PC patients. Materials and methods: Forty-two consecutive HR-PC patients (72.5 ± 6.8 years) were prospectively enrolled, treated by online adaptive MRgSBRT (8 Gy(prostate)/5 Gy(WPRT) × 5 fractions) combined with androgen deprivation therapy (ADT) and followed up (median: 251 days, range: 20−609 days). Clinical outcomes were measured by gastrointestinal (GI) and genitourinary (GU) toxicities according to the Common Terminology Criteria for Adverse Events (CTCAE) Scale v. 5.0, patient-reported quality of life (QoL) with EPIC (Expanded Prostate Cancer Index Composite) questionnaire, and prostate-specific antigen (PSA) responses. Results: All MRgSBRT fractions achieved planning objectives and dose specifications of the targets and organs at risk, and they were successfully delivered. The maximum cumulative acute GI/GU grade 1 and 2 toxicity rates were 19.0%/81.0% and 2.4%/7.1%, respectively. The subacute (>30 days) GI/GU grade 1 and 2 toxicity rates were 21.4%/64.3% and 2.4%/2.4%, respectively. No grade 3 toxicities were reported. QoL showed insignificant changes in urinary, bowel, sexual, and hormonal domain scores during the follow-up period. All patients had early post-MRgSBRT biochemical responses, while biochemical recurrence (PSA nadir + 2 ng/mL) occurred in one patient at month 18. Conclusions: To our knowledge, this is the first prospective study that showed the clinical outcomes of MRgSBRT with concomitant WPRT in HR-PC patients. The early results suggested favorable treatment-related toxicities and encouraging patient-reported QoLs, but long-term follow-up is needed to confirm our early results.

Health Disparities in Prostate Cancer and Approaches to Advance Equitable Care

The American Cancer Society estimates approximately 268,490 new cases of prostate cancer and approximately 34,500 deaths caused by prostate cancer in the United States for 2022. Globally, a total of 1,414,259 new cases of prostate cancer and 375,304 related deaths were reported in 2020. Well-documented health disparities and inequities exist along the continuum of care for prostate cancer management-from screening to diagnostic and staging work-up, surveillance, and treatment-ultimately impacting clinical outcomes. This session-based article discusses innovative patient-centered approaches to advance equitable prostate cancer care. It begins with a review of domestic health disparities in diagnostic imaging and radiotherapy for prostate cancer, and it summarizes barriers and solutions to achieving health equity, such as equity metrics and practice quality improvement projects. Next, a global perspective is provided that describes approaches to address financial and geographic barriers to prostate cancer care, including specific examples of strategies that emphasize the use of the cheapest method of care delivery while maintaining outcomes for drug delivery and radiotherapy.

Secondary Treatment for Men with Localized Prostate Cancer: A Pooled Analysis of PRIAS and ERSPC-Rotterdam Data within the PIONEER Data Platform

Introduction: Treatment choice for localized prostate cancer is complicated, as each treatment option comes with various pros and cons. It is well established that active surveillance (AS), may be ended with a change to curative treatment at the time of disease progression, but it is less clear whether secondary treatment after initial curative treatment is required. As part of the PIONEER project, we quantified the probabilities of treatment change. Methods: A cohort study based on PRIAS and ERSPC-Rotterdam data was conducted. Patients were followed up for 10 years or until the 31st of December 2017. The primary outcome was the incidence of treatment change following initial treatment (i.e., a change to curative treatment following AS or secondary treatment after initial RP/RT). Results: Over a period of 1 to 5 years after initial treatment, the cumulative incidence of treatment change ranged from 3.8% to 42.8% for AS, from 7.6% to 12.1% for radical prostatectomy (RP) and from no change to 5.3% for radiation therapy (RT). While the possibility of treatment change in AS is known, the numbers within a five-year period were substantial. For RP and RT, the rate of change to secondary treatment was lower, but still non-neglectable, with 5 (10)-year incidences up to 12% (20%) and 5% (16%), respectively. Conclusion: This is one of the first studies comparing the incidence of guideline-recommended treatment changes in men receiving different primary treatments (i.e., AS, RT, or RP) for localized prostate cancer (PCa).

Combined hyperthermia and radiotherapy for prostate cancer: a systematic review

Optimization of treatment strategies for prostate cancer patients treated with curative radiation therapy (RT) represents one of the major challenges for the radiation oncologist. Dose escalation or combination of RT with systemic therapies is used to improve tumor control in patients with unfavorable prostate cancer, at the risk of increasing rates and severity of treatment-related toxicities. Elevation of temperature to a supra-physiological level has been shown to both increase tumor oxygenation and reduce DNA repair capabilities. Thus, hyperthermia (HT) combined with RT represents a compelling treatment strategy to improve the therapeutic ratio in prostate cancer patients. The aim of the present systematic review is to report on preclinical and clinical evidence supporting the combination of HT and RT for prostate cancer, discussing future applications and developments of this combined treatment.

Long-Term Outcomes of Dose-Escalated Hypofractionated Radiotherapy in Localized Prostate Cancer

This retrospective study aimed to provide some clinical outcomes regarding effectiveness, toxicity, and quality of life in PCa patients treated with dose-escalated moderately hypofractionated radiation therapy (HFRT). Patients received HFRT to a total dose of 66 Gy in 22 fractions (3 Gy/fraction) delivered via volume modulated arc therapy (VMAT) in 2011-2016. Treatment effectiveness was measured by the biochemical failure-free survival rate. Toxicity was assessed according to the criteria of the Radiation Therapy Oncology Group (RTOG) and quality of life according to the criteria of the European Organization for Research and Treatment of Cancer (EORTC). In this regard, quality of life (QoL) was measured longitudinally, at a median of 2 and 5 years after RT. Enrolled patients had low-risk (40.2%), intermediate-risk (47.5%), and high-risk (12.3%) PCa. Median follow-up was 75 months. The biochemical failure-free survival rate was 94.2%. The incidence of acute grade 2 or higher gastrointestinal (GI) and genitourinary (GU) toxicity was 9.84% and 28.69%, respectively. The incidence rate of late grade 2 or higher GI and GU toxicity was 1.64% and 4.10%, respectively. Expanded Prostate Cancer Index Composite (EPIC) scores showed that the majority of patients maintained their QoL. HFRT to 66 Gy with VMAT was associated with adequate biochemical control, low toxicity and good reported GU and GI quality of life.

Two-Year Toxicity and Efficacy of Carbon Ion Radiotherapy in the Treatment of Localized Prostate Cancer: A Single-Centered Study

Background

We aimed at determining the safety and feasibility of spot-scanning carbon ion radiotherapy (CIRT) for patients with localized prostate cancer.

Methods

We enrolled 118 patients with localized prostate cancer who underwent treatment with spot-scanning CIRT at the Shanghai Proton and Heavy Ion Center (SPHIC) from January 2016 to December 2020. The dose was gradually increased from relative biological effectiveness (RBE)-weighted dose (D_RBE) = 59.2–65.6 Gy in 16 fractions. The primary endpoint was the occurrence of acute and late toxicities, while the secondary endpoints were biochemical relapse-free survival (bRFS), distant metastasis-free survival (DMFS), prostate cancer-specific survival (PCSS), and overall survival (OS).

Results

The median follow-up time was 30.2 months (4.8–62.7 months). Acute grade 1 and 2 genitourinary (GU) toxicities were 15.3% and 18.6%, while acute grade 1 and 2 gastrointestinal (GI) toxicities were 2.5% and 0%, respectively. Late grade 1 and 2 GU toxicities were 4.2% and 1.7%, respectively. No late GI toxicity was observed. Moreover, there were no cases of severe acute or late toxicity (≥ grade 3). No significant association were observed between the factors and the acute GU toxicities, except for clinical target volume (CTV) (p = 0.031) on multivariate analysis. The 2-year bRFS, DMFS, PCSS, and OS were 100%, 100%, 100%, and 98.8%, respectively.

Conclusion

The 2-year outcomes were encouraging, providing additional and useful information on the feasibility and safety of spot-scanning CIRT for treating prostate cancer. Thus, we recommend long-term follow-up and prospective multicentered studies to reinforce the role of CIRT in the management of localized prostate cancer.

Quality of Life Implications of Dose-Escalated External Beam Radiation for Localized Prostate Cancer: Results of a Prospective Randomized Phase 3 Clinical Trial, NRG/RTOG 0126

PURPOSE

External beam radiation therapy (EBRT) dose escalation has been tested in multiple prospective trials. However, the impact on patient reported outcomes (PROs) associated with higher doses of EBRT remain poorly understood. We sought to assess the differences in PROs between men treated with a dose of 70.2 Gy versus 79.2 Gy of EBRT for prostate cancer.

METHODS AND MATERIALS

The phase 3 clinical trial RTOG 0126 randomized 1532 patients with prostate cancer between March 2002 and August 2008 to 79.2 Gy over 44 fractions versus 70.2 Gy over 39 fractions. Eligible patients participated in the PRO data collection. PROs completed included the International Index of Erectile Function Questionnaire (IIEF), Functional Alterations due to Changes in Elimination (FACE), and the Spitzer Quality of Life Index (SQLI). The timepoints for the IIEF were collected pre-entry and at 6, 12, and 24 months. The FACE and SQLI were collected pre-entry and at 3, 6, 12, 18, and 24 months. The impact of EBRT dose to normal structures (penile bulb, rectum, and bladder) on PROs was also examined. Mixed effects models were used to analyze trends across time.

RESULTS

In total, 1144 patients completed baseline IIEF forms and of these, 56%, 64%, and 61% completed the IIEF at 6, 12, and 24 months, respectively; 1123 patients completed the FACE score at baseline and 50%, 61%, 73%, 61%, and 65% completed all 15 items for the FACE metric at timepoints of 3, 6, 12, 18, and 24 months, respectively. Erectile dysfunction at 12 months based on the single question was not significantly different between arms (38.1% for the standard dose radiation therapy arm vs 49.7% for the dose escalated radiation therapy arm; P = .051). Treatment arm (70.2 vs 79.2) had no significant impact on any PRO metrics measured across all collected domains. Comprehensive dosimetric analyses are presented and reveal multiple significant differences to regional organs at risk.

CONCLUSIONS

Compliance with PRO data collection was lower than anticipated in this phase 3 trial. Examining the available data, dose escalated EBRT did not appear to be associated with any detriment to PROs across numerous prospectively collected domains. These data, notwithstanding limitations, add to our understanding of the implications of EBRT dose escalation in prostate cancer. Furthermore, these results illustrate challenges associated with PRO data collection.

Urethral and bladder dose-effect relations for late genitourinary toxicity following external beam radiotherapy for prostate cancer in the FLAME trial

PURPOSE

or objectives The FLAME trial (NCT01168479) showed that by adding a focal boost to conventional fractionated EBRT in the treatment of localized prostate cancer, the five-year biochemical disease-free survival increased, without significantly increasing toxicity. The aim of the present study was to investigate the association between radiation dose to the bladder and urethra and genitourinary (GU) toxicity grade ≥2 in the entire cohort.

MATERIAL AND METHODS

The dose-effect relations of the urethra and bladder dose, separately, and GU toxicity grade ≥2 (CTCAE 3.0) up to five years after treatment were assessed. A mixed model analysis for repeated measurements was used, adjusting for age, diabetes mellitus, T-stage, baseline GU toxicity grade ≥1 and institute. Additionally, the association between the dose and separate GU toxicity subdomains were investigated.

RESULTS

Dose-effect relations were observed for the dose (Gy) to the bladder D2cm³ and urethra D0.1cm³, with adjusted odds ratios of 1.14 (95% CI 1.12-1.16, p<0.0001) and 1.12 (95% CI 1.11-1.14, p<0.0001), respectively. Additionally, associations between the dose to the urethra and bladder and the subdomains urinary frequency, urinary retention and urinary incontinence were observed.

CONCLUSION

Further increasing the dose to the bladder and urethra will result in a significant increase in GU toxicity following EBRT. Focal boost treatment plans should incorporate a urethral dose-constraint. Further treatment optimization to increase the focal boost dose without increasing the dose to the urethra and other organs at risk should be a focus for future research, as we have shown that a focal boost is beneficial in the treatment of prostate cancer.

Patterns of Failure Following External Beam Radiotherapy With or Without an Additional Focal Boost in the Randomized Controlled FLAME Trial for Localized Prostate Cancer

BACKGROUND

Focal dose escalation in external beam radiotherapy (EBRT) showed an increase in 5-yr biochemical disease-free survival in the Focal Lesion Ablative Microboost in Prostate Cancer (FLAME) trial.

OBJECTIVE

To analyze the effect of a focal boost to intraprostatic lesions on local failure-free survival (LFS) and regional + distant metastasis-free survival (rdMFS).

DESIGN, SETTING, AND PARTICIPANTS

Patients with intermediate- or high-risk localized prostate cancer were included in FLAME, a phase 3, multicenter, randomized controlled trial.

INTERVENTION

Standard treatment of 77 Gy to the entire prostate in 35 fractions was compared to an additional boost to the macroscopic tumor of up to 95 Gy during EBRT.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

LFS and rdMFS, measured via any type of imaging, were compared between the treatment arms using Kaplan-Meier and Cox regression analyses. Dose-response curves were created for local failure (LF) and regional + distant metastatic failure (rdMF) using logistic regression.

RESULTS AND LIMITATIONS

A total of 571 patients were included in the FLAME trial. Over median follow-up of 72 mo (interquartile range 58-86), focal boosting decreased LF (hazard ratio [HR] 0.33, 95% confidence interval [CI] 0.14-0.78) and rdMF (HR 0.58, 95% CI 0.35-0.93). Dose-response curves showed that a greater dose to the tumor resulted in lower LF and rdMF rates.

CONCLUSIONS

A clear dose-response relation for LF and rdMF was observed, suggesting that adequate focal dose escalation to intraprostatic lesions prevents undertreatment of the primary tumor, resulting in an improvement rdMF.

PATIENT SUMMARY

Radiotherapy is a treatment option for high-risk prostate cancer. The FLAME trial has shown that a high dose specifically targeted at the tumor within the prostate will result in better disease outcome, with less likelihood of regional and distant disease spread. The FLAME trial is registered on ClinicalTrials.gov as NCT01168479.

Salvage hypofractionated accelerated versus standard radiotherapy for the treatment of biochemical recurrence after radical prostatectomy (SHARE): the protocol of a prospective, randomized, open-label, superiority, multi-institutional trial

BACKGROUND

While several phase III trials have investigated the role of hypofractionated radiotherapy in the definitive treatment of localized prostate cancer, prospective data reporting the outcomes of hypofractionated radiotherapy in the postoperative treatment setting are sparse. Therefore, this study is designed to assess the efficacy and treatment-related toxicity of hypofractionated salvage radiotherapy for the treatment of biochemical recurrence in men who underwent radical prostatectomy. The primary objective of this trial is to investigate whether hypofractionated radiotherapy improves biochemical control compared with conventionally fractionated radiotherapy. In addition, treatment-related toxicity, quality of life, and survival will be evaluated as secondary endpoints.

METHODS

In this prospective, randomized, multi-institutional trial (the SHARE study), patients with intermediate- or high-risk prostate cancer will be randomized to receive either hypofractionated radiotherapy (65 Gy in 2.5-Gy fractions) or conventionally fractionated radiotherapy (66 Gy in 2-Gy fractions). Prostate bed irradiation or elective pelvic nodal irradiation including the prostate bed will be performed using intensity-modulated radiotherapy and daily image guidance. Treatment efficacy will be assessed using the serum tumor marker prostate-specific antigen, and toxicity will be evaluated through both physician- and patient-reported outcomes. Quality of life will also be investigated.

DISCUSSION

This study is designed to demonstrate whether hypofractionated radiotherapy is beneficial in terms of biochemical control and toxicity compared with standard salvage radiotherapy. If hypofractionated radiotherapy is shown to be superior to conventionally fractionated radiotherapy, it will mean that improved biochemical control can be achieved, accompanied by greater patient convenience and more efficient use of medical resources.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03920033. Registered on 18 April 2019.

High rate of local control and cure at 10 years after treatment of prostate cancer with external beam radiotherapy and high-dose-rate brachytherapy: a single centre experience

BACKGROUND AND PURPOSE

To analyse the cumulative incidence of any failure (AF), prostate cancer-specific failure (PCSF), any death (AD), prostate cancer-specific death (PCSD), and local control in 2387 men with prostate cancer (PC), consecutively treated with combined high-dose-rate brachytherapy (HDRBT) and external beam radiotherapy (EBRT) from 1998 to 2010.

MATERIAL AND METHODS

A retrospective, single-institution study of men with localised PC. The mean age was 66 years and 54.7% had high-risk PC according to the Cambridge prognostic group (CPG) classification. The treatment was delivered as EBRT (2 Gy × 25) and HDRBT (10 Gy × 2) with combined androgen blockade (CAB). The median follow-up was 10.2 years.

RESULTS

The cumulative incidence of PCSD at 10 years was 5% [CI 95% 0.04-0.06]. The 10 years PCSD per risk group were: low (L) 0.4%, intermediate favourable (IF) 1%, intermediate unfavourable (IU) 4.3%, high-risk favourable (HF) 5.8%, and high-risk unfavourable (HU) 13.9%. The PCSF rate at 10 years was 16.5% [CI 95% 0.15-0.18]. The PCSF per risk group at 10 years were: L 2.5%, IF 5.5%, IU 15.9%, HF 15.6%, and HU 38.99%. PCSF occurred in 399 men, of whom 15% were found to have local failure. The estimated frequency of local failure in the entire cohort was 1.2%.

CONCLUSIONS

HDRBT combined with EBRT is an effective treatment with long-term overall survival and excellent local control for patients with PC. The low rate of local recurrence among men with relapse suggests that these patients were micro metastasised at time of treatment, which calls for improved methods to detect disseminated disease.

Early outcomes of high-dose-rate brachytherapy combined with ultra-hypofractionated radiation in higher-risk prostate cancer

PURPOSE

This study evaluated outcomes associated with a high-dose-rate (HDR) brachytherapy boost combined with stereotactic body radiation therapy (SBRT) for patients with higher-risk localized prostate cancer.

MATERIALS AND METHODS

We identified 101 patients with National Comprehensive Cancer Network high-risk, unfavorable intermediate-risk, or favorable intermediate-risk with probable extra-prostatic extension treated with HDR brachytherapy (15 Gy x 1 fraction) followed by SBRT (5 Gy x 5 daily fractions to the prostate and/or seminal vesicles and/or pelvic lymph nodes). Androgen deprivation therapy was used in 55.4% of all patients (90% of high-risk, 33% of intermediate-risk). Toxicities according to Common Terminology Criteria for Adverse Events (CTCAE) v4.0 and International Prostate Symptom Scores were prospectively documented at each followup visit. Biochemical relapse was defined as PSA nadir +2ng/mL.

RESULTS

The median follow-up time after SBRT was 24.1 months. No grade ≥3 toxicities were observed. The incidence of acute and late grade 2 gastrointestinal toxicities was both 0.99%. Acute and late grade 2 genitourinary (GU) toxicities were observed in 5.9% and 9.9%, respectively. Median time to a grade 2 GU toxicity was 6 months with a 14% 2-year actuarial rate of grade 2 GU toxicity. Median International Prostate Symptom Scores at 24 months was not significantly different than baseline (6 vs. 5; p = 0.24). Inclusion of pelvic lymph nodes and absence of a rectal spacer were significantly associated with more frequent grade ≥1 GU toxicity, but not grade ≥2 GU or gastrointestinal toxicity. The 2-year biochemical relapse free survival was 97%.

CONCLUSIONS

HDR brachytherapy combined with SBRT was associated with a favorable early toxicity profile and encouraging cancer control outcomes.

Proton vs. photon radiotherapy for MR-guided dose escalation of intraprostatic lesions

BACKGROUND

Dose escalation has been associated with improved biochemical control for prostate cancer. Focusing the high dose on the MRI-defined intraprostatic lesions (IL) could spare the surrounding organs at risk and hence allow further escalation. We compare treatment efficacy between state-of-the-art focally-boosted proton and photon-based radiotherapy, and investigate possible predictive guidelines regarding individualized treatment prescriptions.

MATERIAL AND METHODS

Ten prostate cancer patients with well-defined ILs were selected. Multiparametric MRI was used to delineate ILs, which were transferred to the planning CT via image registration. Pencil beam scanning proton therapy and volumetric modulated arc therapy treatment plans, were created for each patient. Each modality featured 6 plans: (1) moderately hypofractionated dose: 70 Gy to the prostate in 28 fractions, (2)-(6) plan 1 plus additional simultaneous-integrated-boost to ILs to 75.6, 81.2, 86.6, 98 and 112 Gy in 28 fractions. Equivalent dose to 2 Gy-per-fraction (EqD2) was used to calculate tumor control (TCP) and normal tissue complication probabilities (NTCP) for ILs and organs-at-risk.

RESULTS

For both modalities, the maximum necessary dose to achieve TCP > 99% was 98 Gy for very high-risk ILs. For lower risk ILs lower doses were sufficient. NTCP was <25% and 35% for protons and photons at the maximum dose escalation, respectively. For the cases and beam characteristics considered, proton therapy was dosimetrically superior when IL was >4 cc or located <2.5 mm from the rectum.

CONCLUSION

This work demonstrated the potential role for proton therapy in the setting of prostate focal dose escalation. We propose that anatomical characteristic could be used as criteria to identify patients who would benefit from proton treatment.

A comparative analysis between low-dose-rate brachytherapy and external beam radiation therapy for low- and intermediate-risk prostate cancer in Asian men

OBJECTIVE

To report the long-term clinical outcomes of low-risk (LR) and intermediate-risk (IR) prostate cancer patients treated with low-dose-rate brachytherapy (LDR-BT) and external beam radiation therapy (EBRT).

PATIENTS AND METHODS

Men with biopsy-proven low- and intermediate-risk prostate cancer received EBRT and LDR-BT in an Asian academic center from 2000 to 2019 were reviewed. Kaplan-Meier survival analysis was performed to compare biochemical failure-free survival (bFFS) and overall survival (OS) between LDR and EBRT in the low- and intermediate-risk cohorts.

RESULTS

642 patients (521 EBRT and 121 LDR-BT) with low- and intermediate-risk prostate cancer were included for analysis. In the intermediate-risk group, 5- and 10-year bFFS was 96%, 89% and 86%, 61% for LDR-BT and EBRT, respectively. LDR-BT was associated with a statistically significant improvement of bFFS in the intermediate-risk cohort (HR 2.7, p = 0.02). In the low-risk cohort, no difference of bFFS was found between LDR-BT and EBRT (HR 1.9, p = 0.08). Hormone therapy was more common in EBRT than LDR-BT for intermediate-risk group (71% versus 44%, p < 0.05). Prostate cancer-specific mortality was low in both EBRT (1%) and LDR-BT (2%) cohorts. No significant difference in OS was found between LDR-BT and EBRT in low- and intermediate-risk group (HR 2.1, p = 0.2 and HR = 1.7, p = 0.3).

CONCLUSION

In our retrospective study, LDR-BT is associated with superior bFFS compared with EBRT in Asian men with intermediate-risk prostate cancer.

Prospective validation of stringent dose constraints for prostatic stereotactic radiation monotherapy: results of a single-arm phase II toxicity-oriented trial

PURPOSE

There are no safety-focused trials on stereotactic body radiotherapy (SBRT) for localized prostate cancer. This prospective 3‑year phase II trial used binomial law to validate the safety and efficacy of SBRT with stringent organ at risk dose constraints that nevertheless permitted high planning target volume doses.

METHODS

All consecutive ≥ 70-year-old patients with localized prostate adenocarcinoma who underwent SBRT between 2014 and 2018 at the National Radiotherapy Center in Luxembourg were included. Patients with low Cancer of Prostate Risk Assessment (CAPRA) scores (0-2) and intermediate scores (3-5) received 36.25 Gy. High-risk (6-10) patients received 37.5 Gy. Radiation was delivered in 5 fractions over 9 days with Cyberknife-M6™ (Accuray, Sunnyvale, CA, USA). Primary study outcome was Common Terminology Criteria for Adverse Events version 4 (CTCAEv4) genitourinary and rectal toxicity scores at last follow-up. Based on binomial law, SRBT was considered safe in this cohort of 110 patients if there were ≤ 2 severe toxicity (CTCAEv4 grade ≥ 3) cases. Secondary outcomes were biochemical progression-free survival (bPFS) and patient quality of life (QOL), as determined by the IPPS and the Urinary Incontinence QOL questionnaire.

RESULTS

The first 110 patients who were accrued in a total cohort of 150 patients were included in this study and had a median follow-up of 36 months. Acute grade ≥ 3 toxicity never occurred. One transient late grade 3 case was observed. Thus, our SBRT program had an estimated severe toxicity rate of < 5% and was safe at the p < 0.05 level. Overall bPFS was 90%. QOL did not change relative to baseline.

CONCLUSION

The trial validated our SBRT regimen since it was both safe and effective.

Short Androgen Suppression and Radiation Dose Escalation in Prostate Cancer: 12-Year Results of EORTC Trial 22991 in Patients With Localized Intermediate-Risk Disease

PURPOSE

The European Organisation for Research and Treatment of Cancer (EORTC) trial 22991 (NCT00021450) showed that 6 months of concomitant and adjuvant androgen suppression (AS) improves event- (EFS, Phoenix) and clinical disease-free survival (DFS) of intermediate- and high-risk localized prostatic carcinoma, treated by external-beam radiotherapy (EBRT) at 70-78 Gy. We report the long-term results in intermediate-risk patients treated with 74 or 78 Gy EBRT, as per current guidelines.

PATIENT AND METHODS

Of 819 patients randomly assigned between EBRT or EBRT plus AS started on day 1 of EBRT, 481 entered with intermediate risk (International Union Against Cancer TNM 1997 cT1b-c or T2a with prostate-specific antigen (PSA) ≥ 10 ng/mL or Gleason ≤ 7 and PSA ≤ 20 ng/mL, N0M0) and had EBRT planned at 74 (342 patients, 71.1%) or 78 Gy (139 patients, 28.9%). We report the trial primary end point EFS, DFS, distant metastasis-free survival (DMFS), and overall survival (OS) by intention-to-treat stratified by EBRT dose at two-sided α = 5%.

RESULTS

At a median follow-up of 12.2 years, 92 of 245 patients and 132 of 236 had EFS events in the EBRT plus AS and EBRT arm, respectively, mostly PSA relapse (48.7%) or death (45.1%). EBRT plus AS improved EFS and DFS (hazard ratio [HR] = 0.53; CI, 0.41 to 0.70; P < .001 and HR = 0.67; CI, 0.49 to 0.90; P = .008). At 10 years, DMFS was 79.3% (CI, 73.4 to 84.0) with EBRT plus AS and 72.7% (CI, 66.2 to 78.2) with EBRT (HR = 0.74; CI, 0.53 to 1.02; P = .065). With 140 deaths (EBRT plus AS: 64; EBRT: 76), 10-year OS was 80.0% (CI, 74.1 to 84.7) with EBRT plus AS and 74.3% (CI, 67.8 to 79.7) with EBRT, but not statistically significantly different (HR = 0.74; CI, 0.53 to 1.04; P = .082).

CONCLUSION

Six months of concomitant and adjuvant AS statistically significantly improves EFS and DFS in intermediate-risk prostatic carcinoma, treated by irradiation at 74 or 78 Gy. The effects on OS and DMFS did not reach statistical significance.

Anorectal dose-effect relations for late gastrointestinal toxicity following external beam radiotherapy for prostate cancer in the FLAME trial

BACKGROUND AND PURPOSE

The phase III FLAME trial (NCT01168479) showed an increase in five-year biochemical disease-free survival, with no significant increase in toxicity when adding a focal boost to external beam radiotherapy (EBRT) for localized prostate cancer [Kerkmeijer et al. JCO 2021]. The aim of this study was to investigate the association between delivered radiation dose to the anorectum and gastrointestinal (GI) toxicity (grade ≥2).

MATERIAL AND METHODS

All patients in the FLAME trial were analyzed, irrespective of treatment arm. The dose-effect relation of the anorectal dose parameters (D2cm³ and D50%) and GI toxicity grade ≥2 in four years of follow-up was assessed using a mixed model analysis for repeated measurements, adjusted for age, cardiovascular disease, diabetes mellitus, T-stage, baseline toxicity grade ≥1, hormonal therapy and institute.

RESULTS

A dose-effect relation for D2cm³ and D50% was observed with adjusted odds ratios of 1.17 (95% CI 1.13-1.21, p < 0.0001) and 1.20 (95% CI 1.14-1.25, p < 0.0001) for GI toxicity, respectively.

CONCLUSION

Although there was no difference in toxicity between study arms, a higher radiation dose to the anorectum was associated with a statistically significant increase in GI toxicity following EBRT for prostate cancer. This dose-effect relation was present for both large and small anorectal volumes. Therefore, further increase in dose to the anorectum should be weighed against the benefit of focal dose escalation for prostate cancer.