RTOG GU Radiation oncology specialists reach consensus on pelvic lymph node volumes for high-risk prostate cancer

Elective pelvic nodal irradiation in the setting of ultrahypofractionated versus moderately hypofractionated and conventionally fractionated radiotherapy for prostate cancer: Outcomes from 3 prospective clinical trials

Background and purpose

Data is needed regarding the use of ultrahypofractionated radiotherapy (UHRT) in the context of prostate cancer elective nodal irradiation (ENI), and how this compares to conventionally fractionated radiotherapy (CFRT) ENI with CFRT or moderately hypofractionated radiotherapy (MHRT) to the prostate.

Materials and methods

Between 2011-2019, 3 prospective clinical trials of unfavourable intermediate or high-risk prostate cancer receiving CFRT (78 Gy in 39 fractions to prostate; 46 Gy in 23 fractions to pelvis), MHRT (68 Gy in 25 fractions to prostate; 48 Gy to pelvis), or UHRT (35-40 Gy in 5 fractions to prostate +/- boost to 50 Gy to intraprostatic lesion; 25 Gy to pelvis) were conducted. Primary endpoints included biochemical failure (Phoenix definition), and acute and late toxicities (CTCAE v3.0/4.0).

Results

Two-hundred-forty patients were enrolled: 90 (37.5 %) had CFRT, 90 (37.5 %) MHRT, and 60 (25 %) UHRT. Median follow-up time was 71.6 months (IQR 53.6-94.8). Cumulative incidence of biochemical failure (95 % CI) at 5-years was 11.7 % (3.5-19.8 %) for CFRT, 6.5 % (0.8-12.2 %) MHRT, and 1.8 % (0-5.2 %) UHRT, which was not significantly different between treatments (p = 0.38). Acute grade ≥ 2 genitourinary toxicity was significantly worse for UHRT versus CFRT and MHRT, but not for acute grade ≥ 3 genitourinary, or acute gastrointestinal toxicities. UHRT was not associated with worse late toxicities.

Conclusion

ENI with UHRT resulted in similar oncologic outcomes to CFRT ENI with prostate CFRT/MHRT, with worse acute grade ≥ 2 GU toxicity but no differences in late toxicity. Randomized phase 3 trials of ENI using UHRT techniques are much anticipated.

Volumetric Modulated Arc Therapy for High-Risk and Very High-Risk Locoregional Prostate Cancer in the Modern Era: Real-World Experience from an Asian Cohort

This study retrospectively evaluates the clinical outcomes of definitive volumetric modulated arc therapy (VMAT) for high-risk or very high-risk locoregional prostate cancer patients from an Asian institution. Consecutive patients who received VMAT (76 Gy in 38 fractions) between January 2017 and June 2022 were included. Whole pelvic radiotherapy (WPRT) (46 Gy in 23 fractions) was employed for clinically node-negative disease (cN0) and a Roach estimated risk of ≥15%, as well as simultaneous integrated boost (SIB) of 55-57.5 Gy to node-positive (cN1) disease. The primary endpoint was biochemical relapse-free survival (BRFS). Secondary endpoints included radiographic relapse-free survival (RRFS), metastasis-free survival (MFS) and prostate cancer-specific survival (PCSS). A total of 209 patients were identified. After a median follow-up of 47.5 months, the 4-year actuarial BRFS, RRFS, MFS and PCSS were 85.2%, 96.8%, 96.8% and 100%, respectively. The incidence of late grade ≥ 2 genitourinary (GU) and gastrointestinal (GI) toxicity were 15.8% and 11.0%, respectively. No significant difference in cancer outcomes or toxicity was observed between WPRT and prostate-only radiotherapy for cN0 patients. SIB to the involved nodes did not result in increased toxicity. International Society of Urological Pathology (ISUP) group 5 and cN1 stage were associated with worse RRFS (p < 0.05). PSMA PET-CT compared to conventional imaging staging was associated with better BRFS in patients with ISUP grade group 5 (p = 0.039). Five-year local experience demonstrates excellent clinical outcomes. PSMA PET-CT staging for high-grade disease and tailored pelvic irradiation based on nodal risk should be considered to maximize clinical benefit.

Image-Guided Stereotactic Body Radiotherapy on Detectable Prostate Bed Recurrence after Prostatectomy in RT-Naïve Patients

Purpose or Objective-The aim of the study is to evaluate the efficacy and safety of SBRT on detectable prostate bed recurrence in RT-naïve prostate cancer patients.

MATERIALS AND METHODS

Eighty-six patients who underwent SBRT for macroscopic bed recurrence after prostatectomy were retrospectively included. Patients were treated based on mpMRI or choline/PSMA PET.

RESULTS

The median time to biochemical relapse (BCR) after RP was 46 months, with a median PSA at restaging of 1.04 ng/mL. Forty-six patients were staged with mpMRI and choline/PSMA PET, while ten and thirty were treated based on PET and MRI only, respectively. Only one late G ≥ 2 GI toxicity was observed. With a median BCR follow-up of 14 months, twenty-nine patients experienced a BCR with a median PSA at recurrence of 1.66 ng/mL and a median survival free from the event of 40.1 months. The median time to BCR was 17.9 months. Twenty-seven patients had clinical relapse (CR), with a median CR follow-up of 16.27 months and a median time to CR of 23.0 months. Biochemical recurrence-free survival at one and two years was 88% and 66%, respectively, while clinical recurrence-free survival at one and two years was 92% and 82%, respectively. Regarding local relapses, seven were in the field of treatment, while eight of them were outside the field of treatment.

CONCLUSIONS

Data showed that SBRT targeting only the macroscopic bed recurrence instead of the whole prostate bed is safe and effective. Additional data and longer follow-ups will provide a clearer indication of the appropriate treatment and staging methodology for these patients.

Patterns of Failure After Prostate-Only Radiotherapy in High-Risk Prostate Cancer: Implications for Refining Pelvic Nodal Contouring Guidelines

PURPOSE

To study prostate specific membrane antigen - positron emission tomography (Ga68PSMA-PETCT) based patterns of relapse at biochemical failure (BCF) after prostate-only radiotherapy (PORT) in high-risk (HR) prostate cancer and its implications on pelvic contouring recommendations.

METHODS AND MATERIALS

Patients with clinico-radiological high-risk node-negative prostate cancer treated with curative PORT and androgen deprivation therapy (ADT), either within the POP-RT randomised trial or off trial, who underwent a Ga68PSMA-PETCT upon BCF were included. Patterns of regional and distant recurrence on Ga68PSMA-PETCT were studied. Pelvic nodal recurrences were mapped with reference to the superior border of pubic symphysis. Pelvic lymph nodal caudal border (PLNcb) recommendations in the published contouring guidelines (RTOGcb, GETUGcb, PIVOTALcb, NRGcb, GFRUcb) were evaluated.

RESULTS

Of the total 262 patients screened, 68 eligible patients were included (POP-RT trial 35 patients; off-trial 33 patients). Median follow-up was 91 months (IQR, 72-117) and median time to BCF was 65 months (IQR, 49-83). Regional and distant recurrence was seen in 31 (46%) and 31 (46%) patients, respectively. Of the nodal recurrences, nearly half (46%, 14/31) had no distant metastases and 64% (20/31) had a failure in the common iliac nodal region. The lower-most nodal recurrence was 20 mm cranial to the top of pubic symphysis (RTOGcb, GETUGcb, GFRUcb) and 10 mm cranial to the PIVOTALcb. The PLNcb recommended by NRG guideline (NRGcb) had an inter-patient variability of 32 mm, ranging from 16 mm above to 16 mm below the top of pubic symphysis, and the lower most nodal recurrence ranged from 4 mm to 36 mm cranial to NRGcb.

CONCLUSION

Pelvic failures accounted for a major proportion of recurrences after prostate-only radiotherapy, with the caudal most nodal recurrence being 20 mm cranial to the top of pubic symphysis. This could have implications in defining the caudal border of contouring recommendations.

Is Ultrahypofractionated Whole Pelvis Radiation Therapy (WPRT) as Well Tolerated as Conventionally Fractionated WPRT in Patients With Prostate Cancer? Early Results From the HOPE Trial

OBJECTIVE

The aim of this work was to evaluate the acute toxicity and quality-of-life (QOL) impact of ultrahypofractionated whole pelvis radiation therapy (WPRT) compared with conventional WPRT fractionation after high-dose-rate prostate brachytherapy (HDR-BT).

METHODS AND MATERIALS

The HOPE trial is a phase 2, multi-institutional randomized controlled trial of men with prostate-confined disease and National Comprehensive Cancer Network unfavorable intermediate-, high-, or very-high-risk prostate cancer. Patients were randomly assigned to receive conventionally fractionated WPRT (standard arm) or ultrahypofractionated WPRT (experimental arm) in a 1:1 ratio. All patients underwent radiation therapy with 15 Gy HDR-BT boost in a single fraction followed by WPRT delivered with conventional fractionation (45 Gy in 25 daily fractions or 46 Gy in 23 fractions) or ultrahypofractionation (25 Gy in 5 fractions delivered on alternate days). Acute toxicities measured during radiation therapy and at 6 weeks posttreatment were assessed using the clinician-reported Common Terminology Criteria for Adverse Events version 5.0, and QOL was measured using the Expanded Prostate Cancer Index Composite (EPIC-50) and International Prostate Symptom Score (IPSS).

RESULTS

A total of 80 patients were enrolled and treated across 3 Canadian institutions, of whom 39 and 41 patients received external radiation therapy with conventionally fractionated and ultrahypofractionated WPRT, respectively. All patients received androgen deprivation therapy except for 2 patients treated in the ultrahypofractionated arm. The baseline clinical characteristics of the 2 arms were similar, with 51 (63.8%) patients having high or very-high-risk prostate cancer disease. Treatment was well tolerated with no significant differences in the rate of acute adverse events between arms. No grade 4 adverse events or treatment-related deaths were reported. Ultrahypofractionated WPRT had a less detrimental impact on the EPIC-50 bowel total, function, and bother domain scores compared with conventional WPRT in the acute setting. By contrast, more patients treated with ultrahypofractionated WPRT reached the minimum clinical important difference on the EPIC-50 urinary domains. No significant QOL differences between arms were noted in the sexual and hormonal domains.

CONCLUSIONS

Ultrahypofractionated WPRT after HDR-BT is a well-tolerated treatment strategy in the acute setting that has less detrimental impact on bowel QOL domains compared with conventional WPRT.

Moderate hypofractionated radiotherapy to the prostate bed with or without pelvic lymph nodes: a prospective trial

Background

Hypofractionated radiotherapy in the treatment of prostate cancer has been widely studied. However, in the postoperative setting it has been less explored. The objective of this prospective study is to evaluate the safety and efficacy of hypofractionated radiotherapy in postoperative prostate cancer.

Materials and methods

A prospective study was designed to include patients with prostate cancer with an indication of postoperative radiotherapy as adjuvant or salvage. A hypofractionated radiotherapy scheme of 51 Gy in 17 fractions was performed with the possibility of treating the pelvis at a dose of 36 Gy in 12 fractions sequentially. Safety was evaluated based on acute and late toxicity [according to the Radiation Therapy Oncology Group (RTOG) scale and Common Terminology Criteria Adverse Events (CTCAE) v4.03], International Prognostic Scoring System (IPSS) over time, and quality of life.

Results

From August 2020 to June 2022, 31 patients completed treatment and were included in this report. 35.5% of patients received elective treatment of the pelvic nodal areas. Most patients reported minimal or low acute toxicity, with an acute gastrointestinal (GI) and genitourinary (GU) grade 3 or greater toxicity of 3.2% and 0%, respectively. The evolution in time of the IPSS remained without significant differences (p = 0.42). With the exception of a significant improvement in the domains of hormonal and sexual symptoms of the Expanded Prostate Cancer Index Composite (EPIC) questionnaire, the rest of the domains [EPIC, European Organization for Research and Treatment of Cancer (EORTC) Core quality of life questionnaire (C-30) and Prostate Cancer module (PR-25)] were maintained without significant differences over time. With a follow-up of 15.4 months, late GI and GU grade 2 toxicity was reported greater than 0% and 9.6%, respectively.

Conclusions

Hypofractionated radiotherapy in postoperative prostate cancer appears to be safe with low reports of relevant acute or late toxicity. Further follow-up is required to confirm these results.

Trial registration

The protocol was approved by the accredited Medical Ethical Committee of Pontificia Universidad Católica de Chile. All participants accepted and wrote informed consent.

Hypofractionated radiation therapy combined with androgen deprivation therapy for clinically node-positive prostate cancer

PURPOSE

This study aimed to analyze the treatment outcomes of combined definitive radiation therapy (RT) and androgen deprivation therapy (ADT) for clinically node-positive prostate cancer.

MATERIALS AND METHODS

Medical records of 60 patients with clinically suspected metastatic lymph nodes on radiological examination were retrospectively analyzed. Eight patients (13.3%) were suspected to have metastatic common iliac or para-aortic lymph nodes. All patients underwent definitive RT with a dose fractionation of 70 Gy in 28 fractions. ADT was initiated 2-3 months before RT and continued for at least 2 years. Biochemical failure rate (BFR), clinical failure rate (CFR), overall survival (OS), and prostate cancer-specific survival (PCSS) were calculated, and genitourinary and gastrointestinal adverse events were recorded.

RESULTS

The median follow-up period was 5.47 years. The 5-year BFR, CFR, OS, and PCSS rates were 19.1%, 11.3%, 89.0%, and 98.2%, respectively. The median duration of ADT was 2.30 years. BFR and CFR increased after 3 years, and 11 out of 14 biochemical failures occurred after the cessation of ADT. Grade 2 and beyond late genitourinary and gastrointestinal toxicity rates were 5.0% and 13.3%, respectively. However, only two grade 3 adverse events were reported, and no grade 4-5 adverse events were reported. Patients with non-regional lymph node metastases did not have worse BFR, CFR, or adverse event rates.

CONCLUSION

This study reported the efficacy and tolerable toxicity of hypofractionated definitive RT combined with ADT for clinically node-positive prostate cancer. Additionally, selected patients with adjacent non-regional lymph node metastases might be able to undergo definitive RT combined with ADT.

Dose-escalated Salvage Whole-pelvic Radiotherapy for Biochemical Recurrence After Radical Prostatectomy for High-risk Prostate Cancer

Background/Aim

To investigate the institutional experience of dose-escalated salvage whole-pelvic radiotherapy (WPRT) with the simultaneous integrated boost (SIB) technique in patients with biochemical recurrence (BCR) after radical prostatectomy for high-risk prostate cancer.

Patients and Methods

This retrospective study included 21 patients with BCR who received radical prostatectomy for high-risk prostate cancer and underwent salvage RT. Clinical target volume (CTV) of the whole pelvis (CTV56) included the prostate bed, common iliac, external iliac, internal iliac, and obturator lymph node regions. The boost CTV (CTV66) included the prostate bed. Planning target volumes (PTV) were generated by adding a margin of 6-8 mm to CTV (PTV56 and PTV66). Doses of 56.1 and 66 Gy in 33 fractions were delivered to PTV56 and PTV66, respectively.

Results

The 5-year biochemical progression-free survival, overall survival, and cause-specific survival rates were 72%, 94%, and 94%, respectively. A grade 3 late genitourinary toxicity event of gross hematuria was observed in one patient (4%). Acute and late toxicities of grade ≥3, other than gross hematuria, were not observed in any patient.

Conclusion

Dose-escalated salvage WPRT using the SIB technique provides appropriate tumor control without increasing the incident of significant toxicities.

Randomized Trial of Concomitant Hypofractionated Intensity Modulated Radiation Therapy Boost Versus Conventionally Fractionated Intensity Modulated Radiation Therapy Boost for Localized High-Risk Prostate Cancer (pHART2-RCT)

PURPOSE

The aim of this work is to report on the results of a phase 2 randomized trial of moderately hypofractionated (MH) versus conventionally fractionated (CF) radiation therapy to the prostate with elective nodal irradiation.

METHODS AND MATERIALS

This was a single-center, prospective, phase 2 randomized study. Patients with high-risk disease (cT3, prostate-specific antigen level >20 ng/mL, or Gleason score 8-10) were eligible. Patients were randomized to either MH using a simultaneous integrated boost (68 Gy in 25 fractions to prostate; 48 Gy to pelvis) or CF (46 Gy in 23 fractions with a sequential boost to the prostate of 32 Gy in 16 fractions), with long-term androgen deprivation therapy. The primary endpoint was grade ≥2 acute gastrointestinal (GI) and genitourinary (GU) toxicity (Common Terminology Criteria for Adverse Events version 3.0). Secondary endpoints included late GI and GU toxicity, quality of life, and oncologic outcomes.

RESULTS

One-hundred eighty patients were enrolled; 90 were randomized to and received MH and 90 to CF. The median follow-up was 67.4 months. Seventy-five patients (41.7%) experienced a grade ≥2 acute GI and/or GU toxicity, including 34 (37.8%) in the MH and 41 (45.6%) in the CF arms, respectively (P = .29). Late grade ≥2 GI (P = .07) and GU (P = .25) toxicity was not significantly different between arms; however, late grade ≥3 GI toxicity was worse in the MH group (P = .01). There were no statistically significant quality-of-life differences between the 2 treatments. There were no statistically significant differences observed in cumulative incidence of biochemical failure (P = .71) or distant metastasis (P = .31) and overall survival (P = .46).

CONCLUSIONS

MH to the prostate and pelvis with androgen deprivation therapy for men with high-risk localized prostate cancer was not significantly different than CF with regard to acute toxicity, quality of life, and oncologic efficacy. However, late grade ≥3 GI toxicity was more common in the MH arm.

Androgen deprivation alone versus combined with pelvic radiation for adverse events and quality of life in clinically node-positive prostate cancer

The COHORT trial was conducted to compare the efficacy of androgen deprivation therapy (ADT) alone versus combined with radiation therapy (ADT + RT) for clinically node-positive prostate cancer. We reported adverse events and quality of life between the two treatment groups. Fifty-nine patients were randomized to receive ADT alone or ADT + RT and analyzed as per-protocol. Patients allocated to the ADT alone arm received ADT for at least 2 years. Patients in the ADT + RT arm received additional pelvic RT. Higher rates of grade ≥ 2 acute genitourinary (0% vs. 7.1%) and late gastrointestinal adverse events (0% vs. 14.3%) were reported in the ADT + RT arm compared with the ADT alone. However, grade ≥ 2 late genitourinary toxicity was more common in the ADT alone than the ADT + RT arm (9.7% vs. 3.6%). No grade ≥ 3 adverse events were reported. There was no statistically significant difference in EPIC scores between two treatment arms. However, the urinary and bowel domains tended to decrease and recover in the ADT + RT arm. In conclusion, ADT + RT demonstrated higher rates of adverse events compared to ADT alone. However, the addition of RT did not significantly impact the quality of life.

Hypofractionated radiation therapy combined with androgen deprivation therapy for high-risk localized prostate cancer

INTRODUCTION

This study aimed to analyse the treatment outcomes of moderately hypofractionated radiation therapy (RT) combined with androgen deprivation therapy (ADT) and the prognostic implications of prostate-specific antigen (PSA) kinetics in high-risk localized prostate cancer.

METHODS

The medical records of 140 patients who underwent definitive RT (70 Gy in 28 fractions) combined with ADT were retrospectively reviewed. ADT consists of a gonadotropin-releasing hormone agonist and an anti-androgen. Clinical outcomes included the biochemical failure rate (BFR), clinical failure rate (CFR), overall survival (OS) and prostate cancer-specific survival (PCSS). The BFR and CFR were stratified by the PSA nadir and the time to the PSA nadir, respectively. Acute and late genitourinary and gastrointestinal adverse events were also recorded.

RESULTS

The 5-year BFR, CFR, OS and PCSS rates were 9.8%, 4.5%, 90.2% and 98.7%, respectively. Ninety-five (67.9%) patients achieved a PSA nadir of 0.01 ng/mL. Patients with a PSA nadir >0.01 ng/mL had a significantly higher BFR and CFR (BFR, P = 0.001; CFR, P = 0.027), even after adjusting for other prognostic factors [per 0.1 ng/mL; BFR, hazard ratio (HR) 4.440, P < 0.001; CFR, HR 4.338, P = 0.001]. However, the time to the PSA nadir and pre-RT PSA were not significantly associated with the BFR and CFR. Six patients (4.3%) reported grade 3 late adverse events, mostly haematuria and haematochezia.

CONCLUSION

Definitive RT with moderate hypofractionation combined with long-term ADT showed good efficacy for high-risk localized prostate cancer. The lowest PSA nadir was significantly associated with a low recurrence rate, indicating the importance of PSA follow-up.

Safety of Ultrahypofractionated Pelvic Nodal Irradiation in the Definitive Management of Prostate Cancer: Systematic Review and Meta-analysis

PURPOSE

This systematic review and meta-analysis aimed to evaluate the evidence for ultrahypofractionated pelvic nodal irradiation in patients with prostate cancer, with a focus on reported acute and late toxicities.

METHODS AND MATERIALS

A comprehensive search was conducted in 5 electronic databases (PubMed, Scopus, Web of Science, Cochrane Library, ClinicalTrials.gov) from inception until March 23, 2023. Eligible publications included patients with intermediate- and high-risk and node-positive prostate cancer who underwent elective or therapeutic ultrahypofractionated pelvic nodal irradiation. Primary outcomes included the presence of grade ≥2 rates of acute and late gastrointestinal and genitourinary toxicity based on the Common Terminology Criteria for Adverse Events or Radiation Therapy Oncology Group scales. Quality assessment was performed using National Institutes of Health tools for noncontrolled beforeand after (single arm) clinical trials, as well as single-arm observational studies. Because all outcomes were categorical variables, proportion was calculated to estimate the effect size and compare the outcomes after the intervention.

RESULTS

We identified 16 publications that reported the use of ultrahypofractionated radiation therapy to treat the pelvis in prostate cancer. Seven publications met our criteria and were included in the meta-analysis, including 417 patients. The median total dose to the pelvic lymph nodes was 25 Gy (range, 25-28.5 Gy), with a median of 5 fractions. The prostate received a median dose of 40 Gy (range, 35-47.5 Gy). All studies used androgen deprivation therapy for a median duration of 18 months. The median follow-up period was 3 years (range, 0.5-5.6 years). The rates of acute grade ≥2 gastrointestinal and genitourinary toxicity were 8% (95% CI, 1%-15%) and 29% (95% CI, 18%-41%), respectively. For late grade ≥2 gastrointestinal and genitourinary toxicity, the rates were 13% (95% CI, 5%-21%) and 29% (95% CI, 17%-42%), respectively.

CONCLUSIONS

Ultrahypofractionated pelvic nodal irradiation appears to be a safe approach in terms of acute and late genitourinary and gastrointestinal toxicity.

Dose-Intensified Postoperative Radiation Therapy for Prostate Cancer: Long-Term Results From the PKUFH Randomized Phase 3 Trial

PURPOSE

In the randomized, single-center, PKUFH phase 3 trial, dose-intensified (72 Gy) radiation therapy was compared with conventional (66 Gy) radiation therapy. In a previous study, we found no significant difference in biochemical progression-free survival (bPFS) between the 2 cohorts at 4 years. In the current analysis, we provide 7-year outcomes.

METHODS AND MATERIALS

Patients with stage pT3-4, positive surgical margins, or a prostate-specific antigen increase ≥0.2 ng/mL after radical prostatectomy were randomly assigned 1:1 to receive either 72 Gy in 36 fractions or 66 Gy in 33 fractions. All the patients underwent image guided intensity modulated radiation therapy. The primary endpoint was bPFS. Secondary endpoints were distant metastasis-free survival (DMFS), cancer-specific survival (CSS), and overall survival (OS) as estimated using the Kaplan-Meier method.

RESULTS

Between September 2011 and November 2016, 144 patients were enrolled with 73 and 71 in the 72- and 66-Gy cohorts, respectively. At a median follow-up of 89.5 months (range, 73-97 months), there was no difference in 7-year bPFS between the 72- and 66-Gy cohorts (70.3% vs 61.2%; hazard ratio [HR], 0.73; 95% CI, 0.41-1.29; P = .274). However, in patients with a higher Gleason score (8-10), the 72-Gy cohort had statistically significant improvement in 7-year bPFS compared with the 66-Gy cohort (66.5% vs 30.2%; HR, 0.37; 95% CI, 0.17-0.82; P = .012). In addition, in patients with multiple positive surgical margins, the 72-Gy cohort had statistically significant improvement in 7-year bPFS compared with single positive surgical margin (82.5% vs 57.5%; HR, 0.36; 95% CI, 0.13-0.99; P = .037). The 7-year DMFS (88.4% vs 84.9%; HR, 0.93; 95% CI, 0.39-2.23; P = .867), CSS (94.1% vs 95.5%; HR, 1.19; 95% CI, 0.42-3.39; P = .745), and OS (92.8% vs 94.1%; HR, 1.29; 95% CI, 0.51-3.24; P = .594) had no statistical differences between the 72- and 66-Gy cohorts.

CONCLUSIONS

The current 7-year bPFS results confirmed our previous findings that dose escalation (72 Gy) demonstrated no improvement in 7-year bPFS, DMFS, CSS, or OS compared with the 66-Gy regimen. However, patients with a higher Gleason score (8-10) or multiple positive surgical margins might benefit from the 72-Gy regimen, but this requires further prospective research.

Adaptive ultra-hypofractionated whole-pelvic radiotherapy in high-risk and very high-risk prostate cancer on 1.5-Tesla MR-Linac: Estimated delivered dose and early toxicity results

Background

Magnetic resonance (MR)-guided ultra-hypofractionated radiotherapy with whole-pelvic irradiation (UHF-WPRT) is a novel approach to radiotherapy for patients with high-risk (HR) and very high-risk (VHR) prostate cancer (PCa). However, the inherent complexity of adaptive UHF-WPRT might inevitably result in longer on-couch time. We aimed to estimate the delivered dose, study the feasibility and safety of adaptive UHF-WPRT on a 1.5-Tesla MR-Linac.

Methods

Ten patients with clinical stage T3a-4N0-1M0-1c PCa, who consecutively received UHF-WPRT, were enrolled prospectively. The contours of the target and organ-at-risks on the position verification-MR (PV-MR), beam-on 3D-MR(Bn-MR), and post-MR (after radiotherapy delivery) were derived from the pre-MR data by deformable image registration. The physician then manually adjusted them, and dose recalculation was performed accordingly. GraphPad Prism 9 (GraphPad Prism Software Inc.) was utilized for conducting statistical analyses.

Results

In total, we collected 188 MR scans (50 pre-MR, 50 PV-MR, 44 Bn-MR, and 44 post-MR scans). With median 59 min, the mean prostate clinical target volume (CTV)-V100% was 98.59% ± 2.74%, and the mean pelvic CTVp-V100% relative percentages of all scans was 99.60% ± 1.18%. The median V29 Gy change in the rectal wall was -2% (-18% to 20%). With a median follow-up of 9 months, no patient had acute Common Terminology Criteria for Adverse Events (CTCAE) grade 2 or more severe genitourinary (GU) or gastrointestinal (GI) toxicities (0%).

Conclusion

UHF-RT to the prostate and the whole pelvis with concomitant boost to positive nodes using an Adapt-To-Shape (ATS) workflow was technically feasible for patients with HR and VHR PCa, presenting only mild GU and GI toxicities. The estimated target dose during the beam-on phase was clinically acceptable based on the 3D-MR-based dosimetry analysis.

Clinical trial registration

Chinese Clinical Trial Registry ChiCTR2000033382.

Consensus Delineation Guidelines for Pelvic Lymph Node Radiation Therapy of Prostate Cancer: On Behalf of the Francophone Group of Urological Radiation Therapy (GFRU)

PURPOSE

Clinical target volume (CTV) delineation for pelvic lymph nodes in prostate cancer is currently based on 3 consensus guidelines with some inherent discrepancies. To improve the reproducibility in nodal delineation, the Francophone Group of Urological Radiotherapy (Groupe Francophone de Radiothérapie Urologique [GFRU]) worked toward proposing an easily applicable, reproducible, and practice-validated contouring guideline for pelvic nodal CTV.

METHODS AND MATERIALS

The nodal CTV data sets of a high-risk node-negative prostate cancer clinical case contoured by 86 radiation oncologists participating in a GFRU contouring workshop were analyzed. CTV volumes were defined before and after a structured presentation of literature data on lymphatic drainage pathways and patterns of nodal involvement and relapse, illustrated using a reference contour (CRef) defined by 3 GFRU experts. The consistency between the participants' contours and CRef was assessed quantitively by means of the Simultaneous Truth and Performance Level Estimation (STAPLE) method, the Dice coefficient, and the Hausdorff distance and qualitatively using a count map. These results combined with the literature review were thoroughly discussed among GFRU experts to reach a consensus.

RESULTS

From the 86 workshop participants, the volume of the STAPLE CTV was 591 cc compared with 502 cc for CRef. The Dice coefficient of the STAPLE CTV compared with the experts' CRef was 0.736 (±0.084) before and 0.823 (±0.070) after the workshop; the standard deviation decreased from 11.5% to 8.5% over the workshop. The Hausdorff distance of the STAPLE CTV compared with the CRef was 34.5 mm (±12.4) before the workshop and 21.8 mm (±9.3) after the workshop. Four areas of significant interobserver variability were identified, and a consensus was reached.

CONCLUSIONS

Using a robust methodology, our cooperative group proposed an easily applicable, reproducible, and practice-validated guideline for the delineation of the pelvic CTV in prostate cancer, useful for implementation in daily practice and clinical trials.

Long-term findings of rectal endoscopy and rectal bleeding after moderately hypofractionated, intensity-modulated radiotherapy for prostate cancer

To present rectal endoscopic findings and toxicity after definitive moderately hypofractionated, intensity-modulated radiotherapy (IMRT) for prostate cancer. We retrospectively reviewed patients who underwent IMRT for prostate cancer and underwent post-radiotherapy endoscopies between 2008 and 2018. Endoscopic findings were reviewed and graded using Vienna Rectoscopy Score (VRS). We have analyzed the association between endoscopic findings and rectal bleeding, and investigated risk factors for rectal bleeding. Total 162 patients met the inclusion criteria of this study. There was a trend of VRS worsening during the initial 3 years after radiotherapy followed by recovery. Rectal bleeding was highest at 1 year after radiotherapy and improved thereafter. The 5-year cumulative incidence of grade ≥ 2 rectal bleeding was 14.8%. In the multivariable Cox regression analysis, cardiovascular disease (hazard ratio [HR] 2.732, P = 0.037), rectal wall V65 (HR 1.158, P = 0.027), and VRS ≥ 3 in first post-radiotherapy endoscopy (HR 2.573, P = 0.031) were significant risk factors for rectal bleeding. After IMRT for prostate cancer, VRS and rectal bleeding worsened over 1-3 years after radiotherapy and recovered. Cardiovascular disease, rectal wall V65, and VRS ≥ 3 in first post-radiotherapy endoscopy were significant risk factors for rectal bleeding.

Clinical evaluation of deep learning and atlas-based auto-segmentation for organs at risk delineation

Manual delineation of organs at risk and clinical target volumes is essential in radiotherapy planning. Atlas-based auto-segmentation (ABAS) algorithms have become available and been shown to provide accurate contouring for various anatomical sites. Recently, deep learning auto-segmentation (DL-AS) algorithms have emerged as the state-of-the-art in medical image segmentation. This study aimed to evaluate the effect of auto-segmentation on the clinical workflow for contouring different anatomical sites of cancer, such as head and neck (H&N), breast, abdominal region, and prostate. Patients with H&N, breast, abdominal, and prostate cancer (n = 30 each) were enrolled in the study. Twenty-seven different organs at four sites were evaluated. RayStation was used to apply the ABAS. Siemens AI-Rad Companion Organs RT was used to apply the DL-AS. Evaluations were performed with similarity indices using geometric methods, time-evaluation, and qualitative scoring visual evaluations by radiation oncologists. The DL-AS algorithm was more accurate than ABAS algorithm on geometric indices for half of the structures. The qualitative scoring results of the two algorithms were significantly different, and DL-AS was more accurate on many contours. DL-AS had 41%, 29%, 86%, and 15% shorter edit times in the HnN, breast, abdomen, and prostate groups, respectively, than ABAS. There were no correlations between the geometric indices and visual assessments. The time required to edit the contours was considerably shorter for DL-AS than for ABAS. Auto-segmentation with deep learning could be the first step for clinical workflow optimization in radiotherapy.

Proton versus photon therapy for high-risk prostate cancer with dose escalation of dominant intraprostatic lesions: a preliminary planning study

Background and purpose

This study aimed to investigate the feasibility of safe-dose escalation to dominant intraprostatic lesions (DILs) and assess the clinical impact using dose-volume (DV) and biological metrics in photon and proton therapy. Biological parameters defined as late grade ≥ 2 gastrointestinal (GI) and genitourinary (GU) derived from planned (D P) and accumulated dose (D A) were utilized.

Materials and methods

In total, 10 patients with high-risk prostate cancer with multiparametric MRI-defined DILs were investigated. Each patient had two plans with a focal boost to the DILs using intensity-modulated proton therapy (IMPT) and volumetric-modulated arc therapy (VMAT). Plans were optimized to obtain DIL coverage while respecting the mandatory organ-at-risk constraints. For the planning evaluation, DV metrics, tumor control probability (TCP) for the DILs and whole prostate excluding the DILs (prostate-DILs), and normal tissue complication probability (NTCP) for the rectum and bladder were calculated. Wilcoxon signed-rank test was used for analyzing TCP and NTCP data.

Results

IMPT achieved a higher Dmean for the DILs compared to VMAT (IMPT: 68.1 GyRBE vs. VMAT: 66.6 Gy, p < 0.05). Intermediate-high rectal and bladder doses were lower for IMPT (p < 0.05), while the high-dose region (V60 Gy) remained comparable. IMPT-TCP for prostate-DIL were higher compared to VMAT (IMPT: 86%; α/β = 3, 94.3%; α/β = 1.5 vs. VMAT: 84.7%; α/β = 3, 93.9%; α/β = 1.5, p < 0.05). Likewise, IMPT obtained a moderately higher DIL TCP (IMPT: 97%; α/β = 3, 99.3%; α/β = 1.5 vs. VMAT: 95.9%; α/β = 3, 98.9%; α/β = 1.5, p < 0.05). Rectal D A-NTCP displayed the highest GI toxicity risk at 5.6%, and IMPT has a lower GI toxicity risk compared to VMAT-predicted Quantec-NTCP (p < 0.05). Bladder D P-NTCP projected a higher GU toxicity than D A-NTCP, with VMAT having the highest risk (p < 0.05).

Conclusion

Dose escalation using IMPT is able to achieve a high TCP for the DILs, with the lowest rectal and bladder DV doses at the intermediate-high-dose range. The reduction in physical dose was translated into a lower NTCP (p < 0.05) for the bladder, although rectal toxicity remained equivalent.

Elective Nodal Irradiation for Oligorecurrent Nodal Prostate Cancer: Interobserver Variability in the PEACE V-STORM Randomized Phase 2 Trial

Purpose

Consistency in delineation of pelvic lymph node regions for prostate cancer elective nodal radiation therapy is still challenging despite current guidelines. The aim of this study was to evaluate the interobserver variability in elective lymph node delineation in the PEACE V - STORM randomized phase 2 trial for oligorecurrent nodal prostate cancer.

Methods and Materials

Twenty-three centers were asked to delineate the elective pelvic nodal clinical target volume (CTV) of a postoperative oligorecurrent nodal prostate cancer benchmark case using a modified Radiation Therapy Oncology Group (RTOG) 2009 template (upper limit at the L4/L5 interspace). Overall, intersection and overflow volumes, Dice coefficient, Hausdorff distance, and count maps merged with computed tomography images were analyzed.

Results

The mean volume including the 23 nodal CTVs was 430.4 ± 64.1 cm3, larger than the modified RTOG 2009 CTV reference volume (386.1 cm3). The intersection common volume between the modified reference RTOG 2009 and the 23 nodal CTVs was estimated at 83.9%, whereas the overflow volume was 23.4%, mainly located at the level of the presacral and the upper limit of the L4/L5 interspace. The mean Dice coefficient was 0.79 ± 0.02, whereas the mean Hausdorff distance was 27 ± 4.4 mm.

Conclusions

In salvage radiation therapy treatment of oligorecurrent nodal prostate cancer, variations in elective lymph node volume delineation were mainly observed in the presacral and common iliac areas. Routine implementation and diffusion of available contouring guidelines together with a constant evaluation and evidence-based updating are expected to further decrease the existing variability in pelvic node contouring.

Reduction of PTV margins for elective pelvic lymph nodes in online adaptive radiotherapy of prostate cancer patients

BACKGROUND

Cone beam CT (CBCT) based online adaptive radiotherapy (oART) is a new development in radiotherapy. With oART, the requirements for planning target volume (PTV) margins differ from standard therapy because motion occurs during a session. In this study, we aim to evaluate a margin reduction for locally advanced prostate patients treated with oART.

MATERIAL AND METHODS

Intrafraction motion of the elective pelvic lymph nodes was evaluated by two radiation therapists (RTTs) for 150 fractions from 10 prostate patients treated with oART. PTV margins of 3, 4 and 5 mm where added to these lymph nodes for all patients. The seven first patients were treated with 5 mm PTV margin, while the last three patients were treated with 4 mm margin. After treatment, the RTTs reviewed the verification CBCTs and evaluated whether the various PTV margins would have covered the adapted clinical target volume, scoring each fraction as approved, inconclusive or rejected. Couch shifts corresponding to the rigid prostate match between the CBCTs were analyzed with respect to the RTT evaluation.

RESULTS

The RTTs approved a 4 mm margin in 95% of the fractions, while 2% of the fractions were rejected. For a 3 mm margin, 57% of the fractions were approved, while 5% were rejected. The scoring from the two RTTs was consistent; e.g., for 3 mm, one RTT approved 58% of the fractions, while the other approved 55%. If the couch was moved less than 2 mm in any direction, 70% of the fractions were approved for a 3 mm margin, compared to 32% for shifts greater than 2 mm.

CONCLUSION

It is safe to reduce the PTV margin from 5 to 4 mm for the elective pelvic lymph nodes for prostate patients treated with oART. Further margin reductions can be motivated for patients presenting little intrafraction motion.

Updating approach for lexicographic optimization-based planning to improve cervical cancer plan quality

BACKGROUND

To investigate the capability of a not-yet commercially available fully automated lexicographic optimization (LO) planning algorithm, called mCycle (Elekta AB, Stockholm, Sweden), to further improve the plan quality of an already-validated Wish List (WL) pushing on the organs-at-risk (OAR) sparing without compromising target coverage and plan delivery accuracy.

MATERIAL AND METHODS

Twenty-four mono-institutional consecutive cervical cancer Volumetric-Modulated Arc Therapy (VMAT) plans delivered between November 2019 and April 2022 (50 Gy/25 fractions) have been retrospectively selected. In mCycle the LO planning algorithm was combined with the a-priori multi-criterial optimization (MCO). Two versions of WL have been defined to reproduce manual plans (WL01), and to improve the OAR sparing without affecting minimum target coverage and plan delivery accuracy (WL02). Robust WLs have been tuned using a subset of 4 randomly selected patients. The remaining plans have been automatically re-planned by using the designed WLs. Manual plans (MP) and mCycle plans (mCP01 and mCP02) were compared in terms of dose distributions, complexity, delivery accuracy, and clinical acceptability. Two senior physicians independently performed a blind clinical evaluation, ranking the three competing plans. Furthermore, a previous defined global quality index has been used to gather into a single score the plan quality evaluation.

RESULTS

The WL tweaking requests 5 and 3 working days for the WL01 and the WL02, respectively. The re-planning took in both cases 3 working days. mCP01 best performed in terms of target coverage (PTV V95% (%): MP 98.0 [95.6-99.3], mCP01 99.2 [89.7-99.9], mCP02 96.9 [89.4-99.5]), while mCP02 showed a large OAR sparing improvement, especially in the rectum parameters (e.g., Rectum D50% (Gy): MP 41.7 [30.2-47.0], mCP01 40.3 [31.4-45.8], mCP02 32.6 [26.9-42.6]). An increase in plan complexity has been registered in mCPs without affecting plan delivery accuracy. In the blind comparisons, all automated plans were considered clinically acceptable, and mCPs were preferred over MP in 90% of cases. Globally, automated plans registered a plan quality score at least comparable to MP.

CONCLUSIONS

This study showed the flexibility of the Lexicographic approach in creating more demanding Wish Lists able to potentially minimize toxicities in RT plans.

A pilot study of stereotactic body radiotherapy combined with pelvic radiotherapy and GTVp boost based on multiparameter magnetic resonance image in patients with high-risk prostate cancer

This pilot study aimed to explore the preliminary effects and safety of stereotactic body radiotherapy (SBRT) combined with preventive pelvic radiotherapy and primary gross tumor volumes (GTVp) boost in patients with high-risk prostate cancer based on multiparameter magnetic resonance image (mpMRI). Tumors were contoured as GTVp based on mpMRI. The prostate and proximal seminal vesicles were considered as the clinical target volume1. The pelvic lymphatic drainage area constituted clinical target volume 2. Radiation doses were 40Gy or 45Gy/5fractions to planning target volume of primary tumor, 37.5Gy/5f to prostate, seminal vesicle, and positive pelvic lymph nodes, and 25Gy/5f to pelvic synchronously. The treatment was delivered 3 times per week. Volumetric modulated arc radiotherapy and intensity-modulated radiotherapy were used to complete SBRT. The genitourinary (GU) and gastrointestinal (GI) toxicities were evaluated. Quality of life data was also captured. A total of 15 patients were enrolled in this study with a median age of 78 (56-87) from 2017 to 2020. All patients received SBRT. At 3 months after radiotherapy, the proportion of PSA < 0.006 ng/mL was 66.7% (10/15). The 2-year biochemical relapse-free survival was 93.3%. The incidence of grade 1 acute GU side effects was 80% (12/15); the incidence of acute grade 1 GI toxicity was 66.7% (10/15); and no grade 2 or higher acute GU and GI side effects was observed. Two patients presented with temporary late grade 2 GI toxicity. International Prostatic System Score increased rapidly after a transient increase at 1 week (P = .001). There were no significant differences in EORTC quality of life scores in all domains except global health status. In this pilot study, it was revealed that SBRT combined with preventive pelvic radiotherapy and GTVp boost based on mpMRI image was effective and well tolerated for patients with high-risk prostate cancer.

Long-term outcomes of whole-pelvis radiation therapy using volumetric modulated arc therapy for high-risk prostate cancer†

This study investigated the outcomes of whole-pelvis radiation therapy (WPRT) using volumetric modulated arc therapy (VMAT) for high-risk prostate cancer. We retrospectively analysed 112 patients with high-risk prostate cancer who started WPRT at our hospital between August 2011 and August 2015. The prescribed dose was 78 Gy in 39 fractions to the prostate and 46.8 Gy in 26 fractions to the pelvic lymph node (LN) area. All patients received long-term androgen deprivation therapy. We evaluated late gastrointestinal (GI) and genitourinary (GU) toxicities using the Common Terminology Criteria for Adverse Events version 4.0. The median follow-up period for censored cases was 97 (interquartile range [IQR] = 85-108) months. The median age was 72 (IQR = 67-75) years. The high-risk and very-high-risk groups included 41 (36.6%) and 71 patients (63.4%), respectively. The median risk of LN invasion calculated by the Roach formula was 36.9 (IQR = 26.6-56.3) %. The 8-year overall survival, biochemical failure-free survival, disease-free survival and distant metastasis-free survival rates were 88.4, 91.9, 83.8 and 98.0%, respectively. Only one patient experienced common iliac LN recurrence, which was outside the pelvic irradiation area. All patients with recurrent disease were categorized into the very-high-risk group. The 8-year cumulative rates of ≥Grade 2 late GI and GU toxicities were 12.8 and 11.8%, respectively. No patients experienced Grade 4 or higher toxicities. WPRT using VMAT for high-risk prostate cancer was well tolerated and effective.

Prostate-specific antigen kinetics in hypofractionated radiation therapy alone for intermediate- and high-risk localized prostate cancer

Background

This study aimed to evaluate the treatment outcomes and define the prostate-specific antigen (PSA) kinetics as potential prognostic factors in patients with intermediate- or high-risk localized prostate cancer (PCa) who underwent moderately hypofractionated radiation therapy.

Methods

The study retrospectively reviewed the medical records of 149 patients with intermediate- or high-risk localized PCa who underwent definitive radiation therapy (70 Gy in 28 fractions) without androgen deprivation therapy. Clinical outcomes were analyzed based on risk stratification (favorable-intermediate, unfavorable-intermediate, and high-risk). The biochemical failure rate (BFR) and clinical failure rate (CFR) were stratified based on the PSA nadir and the time to the PSA nadir to identify the prognostic effect of PSA kinetics. Acute and late genitourinary and gastrointestinal adverse events were analyzed.

Results

Significant differences were observed in the BFR and CFR according to risk stratification. No recurrence was observed in the favorable intermediate-risk group. The 7-year BFR and CFR for the unfavorable intermediate-risk and high-risk groups were 19.2% and 9.8%, and 31.1% and 25.3%, respectively. Patients with a PSA nadir >0.33 ng/mL or a time to the PSA nadir <36 months had a significantly greater BFR and CFR. The crude rate of grade 3 late adverse events was 3.4% (genitourinary: 0.7%; gastrointestinal: 2.7%). No grade 4-5 adverse event was reported.

Conclusion

A significant difference in clinical outcomes was observed according to risk stratification. The PSA nadir and time to the PSA nadir were strongly associated with the BFR and CFR. Therefore, PSA kinetics during follow-up are important for predicting prognosis.

Prostate-specific membrane antigen positron emission tomography detected local failure after post-prostatectomy radiation therapy: Low rates of out-of-field recurrence validates current Australian prostate bed contouring guidelines

INTRODUCTION

The Australian Faculty of Radiation Oncology Genitourinary Group (FROGG) developed prostate bed clinical target volume (CTV) contouring guidelines which were subsequently used to develop the National EviQ guidelines for adjuvant and salvage post-prostatectomy radiotherapy (PPRT). These guidelines were based mainly upon consensus agreement. With the advent of prostate-specific membrane antigen (PSMA) positron emission tomography (PET), sites of recurrence can now be detected with low prostate-specific antigen (PSA) levels following radical prostatectomy. We evaluated sites of recurrence in patients treated with FROGG/EviQ CTVs to inform upcoming modifications of these guidelines.

METHODS

At our institution, we use the FROGG/EviQ guidelines for PPRT. From 2015, patients with PSA failure following PPRT have been re-staged using PSMA PET imaging. We identified patients with PET-avid local, nodal, and distant recurrences, fusing them with original treatment plans to determine whether recurrences were within or outside the prostate bed CTV. Regional nodal failures were reviewed to determine if they were within current elective node contouring guidelines.

RESULTS

Ninety-four patients had positive PSMA PET following PPRT. Nine (9.6%) recurrences were local, seven being local-only. One local recurrence (1.1%) was just superior to the contoured prostate bed CTV, located within the vas deferens. Seventy-three (77.7%) patients had a component of node failure, with 56 (59.6%) having node-only failure. Sites of nodal relapses were covered by standard contouring guidelines 60.3% of the time.

CONCLUSION

The low recurrence rate outside of current prostate bed CTV contouring guidelines is consistent with other studies using contemporary contouring, and validates the efficacy of the current FROGG/EviQ prostate bed CTV definition.

Hypofractionated Post-Prostatectomy Radiotherapy in 16 Fractions: A Single-Institution Outcome

BACKGROUND

The optimal hypofractionated schedule of post-prostatectomy radiotherapy remains to be established. We evaluated treatment outcomes and toxicity of moderately hypofractionated post-prostatectomy radiotherapy in 16 daily fractions delivered with intensity-modulated radiotherapy. The treatment schedule selection was motivated by limited technology resources and was radiobiologically dose-escalated.

METHODS

One hundred consecutive M0 patients with post-prostatectomy radiotherapy were evaluated. Radiotherapy indication was adjuvant (ART) in 19%, early-salvage (eSRT) in 46% and salvage (SRT) in 35%. The dose prescription for prostate bed planning target volume was 52.8 Gy in 16 fractions of 3.3 Gy. The Common Terminology Criteria v. 4 for Adverse Events scale was used for toxicity grading.

RESULTS

The median follow-up was 61 months. Five-year biochemical recurrence-free survival (bRFS) was 78.6%, distant metastases-free survival (DMFS) was 95.7% and overall survival was 98.8%. Treatment indication (ART or eSRT vs. SRT) was the only significant factor for bRFS (HR 0.15, 95% CI 0.05-0.47, p = 0.001) and DMFS (HR 0.16, 95% CI 0.03-0.90; p = 0.038). Acute gastrointestinal (GI) toxicity grade 2 was recorded in 24%, grade 3 in 2%, acute genitourinary (GU) toxicity grade 2 in 10% of patients, and no grade 3. A cumulative rate of late GI toxicity grade ≥ 2 was observed in 9% and late GU toxicity grade ≥ 2 in 16% of patients.

CONCLUSIONS

The observed results confirmed efficacy and showed a higher than anticipated rate of early GI, late GI, and GU toxicity of post-prostatectomy radiobiologically dose-escalated hypofractionated radiotherapy in 16 daily fractions.

Late Toxicity of Moderately Hypofractionated Intensity-Modulated Proton Therapy Treating the Prostate and Pelvic Lymph Nodes for High-Risk Prostate Cancer

PURPOSE

To evaluate late gastrointestinal (GI) and genitourinary (GU) toxicity of moderately hypofractionated intensity modulated proton therapy (IMPT) targeting the prostate and pelvic lymph nodes.

METHODS AND MATERIALS

A target accrual of 56 patients with high-risk or unfavorable intermediate risk prostate cancer were enrolled into a prospective study (ClinicalTrials.gov: NCT02874014) of moderately hypofractionated IMPT. IMPT with pencil beam scanning was used to deliver 6750 and 4500 cGy relative biological effectiveness in 25 daily fractions simultaneously to the prostate and pelvic lymph nodes, respectively. All received androgen deprivation therapy. Late GI and GU toxicity was prospectively assessed using Common Terminology Criteria for Adverse Events version 4.0, at baseline, weekly during radiation therapy, 3-month postradiation therapy, and then every 6 months. Actuarial rates of late GI and GU toxicity were estimated using Kaplan-Meier method.

RESULTS

Median age was 75.5 years. Fifty-four patients were available for late toxicity evaluation. Median follow-up was 43.9 months (range, 16-66). The actuarial rate of late grade ≥2 GI toxicity at both 2 and 3 years was 7.4% (95% confidence interval [CI], 0.2%-14.2%). The actuarial rate of late grade 3 GI toxicity at both 2 and 3 years was 1.9% (95% CI, 0%-5.4%). One patient experienced grade 3 GI toxicity with proctitis. The actuarial rate of late grade ≥2 GU toxicity was 20.5% (95% CI, 8.9%-30.6%) at 2 years, and 29.2 % (95% CI, 15.5%-40.7%) at 3 years. None had grade 3 GU toxicity. The presence of baseline GU symptoms was associated with a higher likelihood of experiencing late grade 2 GU toxicity.

CONCLUSIONS

A moderately hypofractionated IMPT targeting the prostate and regional pelvic lymph nodes was generally well tolerated. Patients with pre-existing GU symptoms had a higher rate of late grade 2 GU toxicity. A phase 3 study is needed to assess any therapeutic gain of IMPT, in comparison with photon-based radiation therapy.

Comparison of Hormone-Sensitive Oligorecurrent Prostate Cancer Patients Based on Routine Use of Choline and/or PSMA PET/CT to Guide Metastasis-Directed Therapy

BACKGROUND

In hormone-sensitive oligorecurrent prostate cancer (PC), the literature showed [68Ga]Ga-PSMA (PSMA) and [18F]F-choline (FCH) PET/CT can successfully guide metastasis-directed therapies (MDT). This observational retrospective study aimed to explore, in routine use, the impact of FCH or PSMA PET/CT in guiding MDT for hormone-sensitive oligometastatic PC at different recurrences.

METHODS

In 2017-2020, patients initially treated with radical prostatectomy but, in biochemical recurrence (with PSA ≤ 2 ng/mL), diagnosed as oligometastatic based on FCH or PSMA PET/CT, were identified. MDT was stereotactic body radiotherapy (SBRT), elective nodal or prostate bed radiotherapy ± boost and ± androgen deprivation therapy (ADT). The primary endpoint was biochemical relapse-free survival (BR-FS), defined as a PSA increase ≥ 0.2 ng/mL above the nadir and increasing over two successive samples and the secondaries were ADT-free survival (ADT-FS).

RESULTS

123 patients (70 PSMA and 53 FCH) were included. The median follow-up was 42.2 months. The median BR-FS was 24.7 months in the PSMA group versus 13.0 months in the FCH group (p = 0.008). Similarly, ADT-FS (p = 0.001) was longer in patients in the PSMA group. In multivariate analysis, a short PSA doubling time before imaging (p = 0.005) and MDT with SBRT (p = 0.001) were poor prognostic factors for BR-FS.

CONCLUSIONS

Routine use of FCH or PSMA PET/CT in hormone-sensitive PC showed an advantage for using PSMA PET/CT to guide MDT in terms of BR-FS and ADT-FS in patients with low PSA value. Prospective studies are needed to confirm these hypotheses.

Sentinel Node Procedure to Select Clinically Localized Prostate Cancer Patients with Occult Nodal Metastases for Whole Pelvis Radiotherapy

Background

Accurate identification of men who harbor nodal metastases is necessary to select patients who most likely benefit from whole pelvis radiotherapy (WPRT). Limited sensitivity of diagnostic imaging approaches for the detection of nodal micrometastases has led to the exploration of the sentinel lymph node biopsy (SLNB).

Objective

To evaluate whether SLNB can be used as a tool to select pathologically node-positive patients who likely benefit from WPRT.

Design setting and participants

We included 528 clinically node-negative primary prostate cancer (PCa) patients with an estimated nodal risk of >5% treated between 2007 and 2018.

Intervention

A total of 267 patients were directly treated with prostate-only radiotherapy (PORT; non-SLNB group), while 261 patients underwent SLNB to remove lymph nodes directly draining from the primary tumor prior to radiotherapy (SLNB group); pN0 patients were treated with PORT, while pN1 patients were offered WPRT.

Outcome measurements and statistical analysis

Biochemical recurrence-free survival (BCRFS) and radiological recurrence-free survival (RRFS) were compared using propensity score weighted (PSW) Cox proportional hazard models.

Results and limitations

The median follow-up was 71 mo. Occult nodal metastases were found in 97 (37%) SLNB patients (median metastasis size: 2 mm). Adjusted 7-yr BCRFS rates were 81% (95% confidence interval [CI] 77-86%) in the SLNB group and 49% (95% CI 43-56%) in the non-SLNB group. The corresponding adjusted 7-yr RRFS rates were 83% (95% CI 78-87%) and 52% (95% CI 46-59%), respectively. In the PSW multivariable Cox regression analysis, SLNB was associated with improved BCRFS (hazard ratio [HR] 0.38, 95% CI 0.25-0.59, p < 0.001) and RRFS (HR 0.44, 95% CI 0.28-0.69, p < 0.001). Limitations include the bias inherent to the study's retrospective nature.

Conclusions

SLNB-based selection of pN1 PCa patients for WPRT was associated with significantly improved BCRFS and RRFS compared with (conventional) imaging-based PORT.

Patient summary

Sentinel node biopsy can be used to select patients who will benefit from the addition of pelvis radiotherapy. This strategy results in a longer duration of prostate-specific antigen control and a lower risk of radiological recurrence.

A Contemporary Report of Low-Dose-Rate Brachytherapy for Prostate Cancer Using MRI for Risk Stratification: Disease Outcomes and Patient-Reported Quality of Life

PURPOSE

We examined a prospective consecutive cohort of low dose rate (LDR) brachytherapy for prostate cancer to evaluate the efficacy of monotherapy for unfavorable-intermediate risk (UIR) disease, and explore factors associated with toxicity and quality of life (QOL).

METHODS

149 men with prostate cancer, including 114 staged with MRI, received Iodine-125 brachytherapy alone (144-145 Gy) or following external beam radiation therapy (110 Gy; EBRT). Patient-reported QOL was assessed by the Expanded Prostate Index Composite (EPIC) survey, and genitourinary (GU) and gastrointestinal (GI) toxicity were prospectively recorded (CTC v4.0). Global QOL scores were assessed for decline greater than the minimum clinically important difference (MCID). Univariate analysis (UVA) was performed, with 30-day post-implant dosimetry covariates stratified into quartiles. Median follow-up was 63 mo.

RESULTS

Men with NCCN low (n = 42) or favorable-intermediate risk (n = 37) disease were treated with brachytherapy alone, while most with high-risk disease had combined EBRT (n = 17 of 18). Men with UIR disease (n = 52) were selected for monotherapy (n = 42) based on clinical factors and MRI findings. Freedom from biochemical failure-7 yr was 98%. Of 37 men with MRI treated with monotherapy for UIR disease, all 36 men without extraprostatic extension were controlled. Late Grade 2+/3+ toxicity occurred in 55/3% for GU and 8/2% for GI, respectively. Fifty men were sexually active at baseline and had 2 yr sexual data; 37 (74%) remained active at 2 yr. Global scores for urinary incontinence (UC), urinary irritation/obstruction (UIO), bowel function, and sexual function (SF) showed decreases greater than the MCID (p < 0.05) in UC at 2 mo, UIO at 2 and 6 mo, and SF at 2-24 mo, and >5 yr. Analysis did not reveal any significant associations with any examined rectal or urethral dosimetry for late toxicity or QOL.

CONCLUSION

Disease outcomes and patient-reported QOL support LDR brachytherapy, including monotherapy for UIR disease.

Mask R-CNN assisted 2.5D object detection pipeline of 68Ga-PSMA-11 PET/CT-positive metastatic pelvic lymph node after radical prostatectomy from solely CT imaging

Prostate-specific membrane antigen (PSMA) positron emission tomography (PET)/computed tomography (CT) is a molecular and functional imaging modality with better restaging accuracy over conventional imaging for detecting prostate cancer in men suspected of lymph node (LN) progression after definitive therapy. However, the availability of PSMA PET/CT is limited in both low-resource settings and for repeating imaging surveillance. In contrast, CT is widely available, cost-effective, and routinely performed as part of patient follow-up or radiotherapy workflow. Compared with the molecular activities, the morphological and texture changes of subclinical LNs in CT are subtle, making manual detection of positive LNs infeasible. Instead, we harness the power of artificial intelligence for automated LN detection on CT. We examined ⁶⁸Ga-PSMA-11 PET/CT images from 88 patients (including 739 PSMA PET/CT-positive pelvic LNs) who experienced a biochemical recurrence after radical prostatectomy and presented for salvage radiotherapy with prostate-specific antigen < 1 ng/mL. Scans were divided into a training set (nPatient = 52, nNode = 400), a validation set (nPatient = 18, nNode = 143), and a test set (nPatient = 18, nNodes = 196). Using PSMA PET/CT as the ground truth and consensus pelvic LN clinical target volumes as search regions, a 2.5-dimensional (2.5D) Mask R-CNN based object detection framework was trained. The entire framework contained whole slice imaging pretraining, masked-out region fine-tuning, prediction post-processing, and "window bagging". Following an additional preprocessing step-pelvic LN clinical target volume extraction, our pipeline located positive pelvic LNs solely based on CT scans. Our pipeline could achieve a sensitivity of 83.351%, specificity of 58.621% out of 196 positive pelvic LNs from 18 patients in the test set, of which most of the false positives can be post-removable by radiologists. Our tool may aid CT-based detection of pelvic LN metastasis and triage patients most unlikely to benefit from the PSMA PET/CT scan.

How smart is artificial intelligence in organs delineation? Testing a CE and FDA-approved Deep-Learning tool using multiple expert contours delineated on planning CT images

Background

A CE- and FDA-approved cloud-based Deep learning (DL)-tool for automatic organs at risk (OARs) and clinical target volumes segmentation on computer tomography images is available. Before its implementation in the clinical practice, an independent external validation was conducted.

Methods

At least a senior and two in training Radiation Oncologists (ROs) manually contoured the volumes of interest (VOIs) for 6 tumoral sites. The auto-segmented contours were retrieved from the DL-tool and, if needed, manually corrected by ROs. The level of ROs satisfaction and the duration of contouring were registered. Relative volume differences, similarity indices, satisfactory grades, and time saved were analyzed using a semi-automatic tool.

Results

Seven thousand seven hundred sixty-five VOIs were delineated on the CT images of 111 representative patients. The median (range) time for manual VOIs delineation, DL-based segmentation, and subsequent manual corrections were 25.0 (8.0-115.0), 2.3 (1.2-8) and 10.0 minutes (0.3-46.3), respectively. The overall time for VOIs retrieving and modification was statistically significantly lower than for manual contouring (p<0.001). The DL-tool was generally appreciated by ROs, with 44% of vote 4 (well done) and 43% of vote 5 (very well done), correlated with the saved time (p<0.001). The relative volume differences and similarity indexes suggested a better inter-agreement of manually adjusted DL-based VOIs than manually segmented ones.

Conclusions

The application of the DL-tool resulted satisfactory, especially in complex delineation cases, improving the ROs inter-agreement of delineated VOIs and saving time.

Dosimetric and Hematologic Implications of Prostate-Only Versus Whole Pelvic Radiotherapy: Results of the Multicentric Phase 3 PROPER Study

Objectives: The aim is to evaluate the incidental dose to the lymphatic regions in prostate-only radiotherapy (PORT) and to compare hematological outcome between PORT and whole pelvic radiotherapy (WPRT) in node-positive prostate cancer (pN1 PCa), in the era of modern radiotherapy techniques. Methods: We performed a prospective phase 3 trial in which a total of 64 pN1 PCa patients were randomized between PORT (ARM A) and WPRT (ARM B) delivered with volumetric-modulated arc therapy (VMAT). The lymph node (LN) regions were delineated separately and differences between groups were calculated using Welch t-tests. Hematological toxicity was scored according to common terminology criteria for adverse events (CTCAE) version 4.03. To evaluate differences in the evolution of red blood cell (RBC), white blood cell (WBC), and platelet count over time between PORT and WPRT, 3 linear mixed models with a random intercept for the patient was fit with model terms randomization group, study time point, and the interaction between both categorical predictors. Results: Except for dose to the obturator region, the incidental dose to the surrounding LN areas was low in ARM A. None of the patients developed severe hematological toxicity. The change in RBC from time point pre-external beam radiotherapy (EBRT) to month 3 and for WBC from time point pre-EBRT to months 3 and 12 was significantly different with ARM B showing a larger decrease. Conclusion: The incidental dose to the lymphatic areas becomes neglectable when PORT is delivered with VMAT. Hematological toxicity is very low after WPRT with VMAT and when bone marrow constraints are used for planning, although WPRT causes a decrease in RBC and WBC count over time.

Prostate-specific Membrane Antigen Positron Emission Tomography/Computed Tomography-based Lymph Node Atlas for Salvage Radiotherapy in Patients with Recurrent Prostate Cancer: A Validation of the New NRG Oncology 2020 guideline

BACKGROUND

Approximately 20-40% of patients with prostate cancer (PC) who undergo radical prostatectomy (RP) experience relapse, with the majority of these cases developing pelvic lymph node (LN) metastases. Taking new data from the prostate-specific membrane antigen (PSMA) positron emission tomography (PET) era into account, the Radiation Therapy Oncology Group (RTOG) 2009 contouring guideline for the pelvic LNs from 2009 was updated by the NRG Oncology group in 2020 (NRG 2020).

OBJECTIVE

To evaluate and validate the updated NRG 2020 guideline with our established LN atlas.

DESIGN, SETTING, AND PARTICIPANTS

We screened 1653 PSMA PET/computed tomography (CT) data sets for patients with biochemical relapse who underwent a PET scan between November 2012 and November 2017. After screening, we developed an LN atlas using data from 233 patients.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

We evaluated LN overlap (OL) with the RTOG 2009 and NRG 2020 contouring guidelines. OL was defined as within (>90%), partly within (10-90%), or outside (<10%).

RESULTS AND LIMITATIONS

In comparison to the RTOG 2009 guideline, 403 (52%), 134 (17%), and 241 (31%) of the LNs were not, were partly, or were fully covered within the overall group, respectively. By contrast, using the NRG 2020 guideline, 302 (39%), 190 (24%), and 286 (37%) of the LNs were not, were partly, or were fully covered, respectively (p < 0.001). Limitations include the retrospective design with missing data and no histopathological confirmation of the PET results.

CONCLUSIONS

The updated NRG 2020 contouring guideline improves coverage of the pelvic LNs in patients undergoing salvage radiation therapy. However, PET/CT should be considered whenever possible to ensure coverage of untypical LN spread.

PATIENT SUMMARY

We compared the 2009 and 2020 guidelines on the radiation area for the pelvis for patients with recurrent prostate cancer that has spread to lymph nodes. The newer guideline provides better coverage of pelvic lymph nodes than the older one and is useful in planning radiation therapy. However, a scan of the pelvis using the newest technique should be considered for individual patients to ensure coverage of untypical lymph nodes.

Dosimetric impact of rotational set-up errors in high-risk prostate cancer

Introduction: Cone-beam computed tomography (CBCT) provides an excellent solution to quantitative assessment and correction of patient set-up errors during radiotherapy. However, most linear accelerators are equipped with conventional therapy tables that can be moved in three translational directions and perform only yaw rotation. Uncorrected roll and pitch result in rotational set-up errors, particularly when the distance from the isocenter to the target border is large. The aim of this study was to investigate the impact of rotational errors on the dose delivered to the clinical target volume (CTV), the planning target volume (PTV) and organs at risk (OAR).

Material and methods: 30 patients with prostate cancer treated with VMAT technique had daily CBCT scans (840 CBCTs in total) prior to treatment delivery. The rotational errors remaining after on-line correction were retrospectively analysed. The sum plans simulating the dose distribution during the treatment course were calculated for selected patients with significant rotational errors.

Results: The dose delivered to the prostate bed CTV reported in the sum plan was not lower than in the original plan for all selected patients. For four patients from the selected group, the D98% for prostate bed PTV was less than 95%. The V47.88Gy for pelvic lymph nodes PTV was less than 98% for two of the selected patients.

Conclusions: The analysis of the dosimetric parameters showed that the impact of uncorrected rotations is not clinically significant in terms of the dose delivered to OAR and the dose coverage of CTV. However, the PTV dose coverage is correlated with distance away from the isocenter and is smaller than planned.

Comprehensive dosimetric and clinical evaluation of lexicographic optimization-based planning for cervical cancer

AIM

In this study, a not yet commercially available fully-automated lexicographic optimization (LO) planning algorithm, called mCycle (Elekta AB, Stockholm, Sweden), was validated for cervical cancer.

MATERIAL AND METHODS

Twenty-four mono-institutional consecutive treatment plans (50 Gy/25 fx) delivered between November 2019 and April 2022 were retrospectively selected. The automatic re-planning was performed by mCycle, implemented in the Monaco TPS research version (v5.59.13), in which the LO and Multicriterial Optimization (MCO) are coupled with Monte Carlo calculation. mCycle optimization follows an a priori assigned priority list, the so-called Wish List (WL), representing a dialogue between the radiation oncologist and the planner, setting hard constraints and following objectives. The WL was tuned on a patient subset according to the institution's clinical protocol to obtain an optimal plan in a single optimization. This robust WL was then used to automatically re-plan the remaining patients. Manual plans (MP) and mCycle plans (mCP) were compared in terms of dose distributions, complexity (modulation complexity score, MCS), and delivery accuracy (perpendicular diode matrices, gamma analysis-passing ratio, PR). Their clinical acceptability was assessed through the blind choice of two radiation oncologists. Finally, a global quality score index (SI) was defined to gather into a single number the plan evaluation process.

RESULTS

The WL tuning requested four patients. The 20 automated re-planning tasks took three working days. The median optimization and calculation time can be estimated at 4 h and just over 1 h per MP and mCP, respectively. The dose comparison showed a comparable organ-at-risk spare. The planning target volume coverage increased (V95%: MP 98.0% [95.6-99.3]; mCP 99.2%[89.7-99.9], p >0.05). A significant increase has been registered in MCS (MP 0.29 [0.24-0.34]; mCP 0.26 [0.23-0.30], p <0.05) without affecting delivery accuracy (PR (3%/3mm): MP 97.0% [92.7-99.2]; mCP 97.1% [95.0-98.6], p >0.05). In the blind choice, all mCP results were clinically acceptable and chosen over MP in more than 75% of cases. The median SI score was 0.69 [0.41-0.84] and 0.73 [0.51-0.82] for MP and mCP, respectively (p >0.05).

CONCLUSIONS

mCycle plans were comparable to clinical manual plans, more complex but accurately deliverable and registering a similar SI. Automated plans outperformed manual plans in blinded clinical choice.

VMAT partial arc technique decreases dose to organs at risk in whole pelvic radiotherapy for prostate cancer when compared to full arc VMAT and IMRT

Whole pelvic radiotherapy (WPRT) can sterilize microscopic lymph node metastases in treatment of prostate cancer. WPRT, compared to prostate only radiotherapy (PORT), is associated with increased acute gastrointestinal, and hematological toxicities. To further explore minimizing normal tissue toxicities associated with WPRT in definitive IMRT for prostate cancer, this planning study compared dosimetric differences between static 9-field-IMRT, full arc VMAT, and mixed partial-full arc VMAT techniques. In this retrospective study, 12 prostate cancer patients who met the criteria for WPRT were randomly selected for this study. The initial volume, PTV46, included the prostate, seminal vesicles, and pelvic nodes with margin and was prescribed to 4600 cGy. The cone-down volume, PTV78, included the prostate and proximal seminal vesicles with margin to a total dose of 7800 cGy. For each CT image set, 3 plans were generated for each of the PTVs: an IMRT plan, a full arc (FA) VMAT plan, and a mixed partial-full arc (PFA) VMAT plan, using 6MV photons energy. According to RTOG protocols none of the plans had a major Conformity Index (CI) violation by any of the 3 planning techniques. PFA plan had the best mean CI index of 1.00 and significantly better than IMRT (p = 0.03) and FA (p = 0.007). For equivalent PTV coverage, the average composite gradient index of the PFA plans was better than the IMRT and the FA plans with values 1.92, 2.03, and 2.01 respectively. The defference was statistically significant between PFA/IMRT and PFA/FA, with p- values of < 0.001. The IMRT plans and the PFA plans provided very similar doses to the rectum, bladder, sigmoid colon, and femoral heads, which were lower than the dose in the FA plans. There was a significant decrease in the mean dose to the rectum from 4524 cGy with the FA to 4182 cGy with the PFA and 4091 cGy with IMRT (p < 0.001). The percent of rectum receiving 4000 cGy was also the highest with FA at 66.1% compared to 49.9% (PFA) and 47.5% (IMRT). There was a significant decrease in the mean dose to the bladder from 3922 cGy (FA) to 3551 cGy (PFA) and 3612 cGy (IMRT) (p < 0.001). The percent of bladder receiving 4000 cGy was also the highest with FA at 45.4% compared to 36.6% (PFA) and 37.4% (IMRT). The average mean dose to the sigmoid colon decreased from 4177 cGy (FA) to 3893 cGy (PFA) and 3819 cGy (IMRT). The average mean dose to the femoral heads decreased from 2091 cGy (FA) to 2026 cGy (PFA) and 1987 cGy (IMRT). Considering the improvement in plan quality indices recorded in this study including the dose gradient and the dose to organs at risk, mixed partial-full arc plans may be the preferred VMAT treatment technique over full arc plans for prostate cancer treatments that include nodal volumes.

A Phase II prospective study of hypofractionated proton therapy of prostate and pelvic lymph nodes: Acute effects on patient-reported quality of life

BACKGROUND

The objective of this study was to report acute changes in patient-reported quality of life (PRQOL) using the 26-item Expanded Prostate Index Composite (EPIC-26) questionnaire in a prospective study using hypofractionated intensity-modulated proton beam therapy (H-IMPT) targeting the prostate and the pelvic lymph nodes for high-risk or unfavorable intermediate-risk prostate cancer.

METHODS

Fifty-five patients were enrolled. H-IMPT consisted of 45 GyE to the pelvic lymph nodes and 67.5 GyE to the prostate and seminal vesicles in 25 fractions. PRQOL was assessed with the urinary incontinence (UI), urinary irritative/obstructive symptoms (UO), and bowel function (BF) domains of EPIC-26 questionnaire. Mean changes in domain scores were analyzed from pretreatment to the end of treatment and 3 months posttreatment. A clinically meaningful change (or minimum important change) was defined as a score change > 50% of the baseline standard deviation.

RESULTS

The mean scores of UO, UI, and BF at baseline were 84.6, 91.1, and 95.3, respectively. At the end of treatment, there were statistically significant and clinically meaningful declines in UO and BF scores (-13.5 and -2.3, respectively), while the decline in UI score was statistically significant but not clinically meaningful (-13.7). A clinically meaningful decline in UO, UI, and BF scores occurred in 53.5%, 22.7%, and 73.2% of the patients, respectively. At 3 months posttreatment, all three mean scores showed an improvement, with fewer patients having a clinically meaningful decline in UO, UI, and BF scores (18.4%, 20.5%, and 45.0%, respectively). There was no significant reduction in the mean UO and UI scores compared to baseline, although the mean BF score remained lower than baseline and the difference was clinically meaningful.

CONCLUSIONS

UO, UI, and BF scores of PRQOL declined at the end of H-IMPT. UO and UI scores showed improvement at 3 months posttreatment and were similar to the baseline scores. However, BF score remained lower at 3 months posttreatment with a clinically meaningful decline.

The role of multiparametric mri in the diagnosis of local recurrence after radical prostatectomy and before salvage radiotherapy

PURPOSE

Assess multiparametric-MRI (mp-MRI) diagnostic accuracy in the detection of local recurrence of Prostate Cancer (PCa) after Radical Prostatectomy (PR) and before Radiation Therapy (RT).

MATERIALS AND METHODS

A total of 188 patients underwent 1.5-T mp-MRI after RP before RT. Patients were divided into two groups: with biochemical recurrence (group A) and without but with high risk of local recurrence (group B). Continuous variables were compared between two groups using T-Student; categoric variables were analyzed using Pearson chi-square. ROC analysis was performed considering PSA before RT, ISUP, pT and pN as grouping variables.

RESULTS

PCa recurrence (reduction of PSA levels after RT) was 89.8% in the group A and 80.3% in the group B. Comparing patients with and without PCa recurrence, there was a significant difference in PSA values before RT for group A and for PSA values before RT and after RT for group B. In group A, there was a significant correlation between PSA before RT and diameter of recurrence and between PSA before RT and time spent before recurrence. The mp-MRI diagnostic accuracy in detecting PCa local recurrence after RP is of 62.2% in group A and 38% in group B. DWI is the most specific MRI-sequence and DCE the most sensitive. For PSA = 0.5 ng/ml, the AUC decreases while sensitivity and accuracy increase for each MRI-sequence. For PSA = 0.9 ng/ml, DCE-AUC increases significantly.

CONCLUSION

mp-MRI should always be performed before RT when a recurrence is suspected. New scenarios can be opened considering the role of DWI for PSA ≤ 0.5 ng/ml.

Common iliac node positive prostate cancer treated with curative radiotherapy: N1 or M1a?

PURPOSE

Common iliac (CI) nodes are staged as (oligo)metastatic M1a for prostate cancer. It is unclear if outcomes of pelvic node-positive (cN1) differ from CI node-positive (CI-M1a) prostate cancer after curative treatment. Present study compares outcomes in these patients treated with radical whole pelvic radiotherapy and long-term ADT.

MATERIALS AND METHODS

Patients with node positive adenocarcinoma prostate were identified, either CI-M1a or cN1, from a prospectively maintained database. Over 75% of these patients were staged with Ga68PSMA-PETCT at diagnosis. All patients received long-term ADT and moderately or extremely hypofractionated radiotherapy to the prostate and pelvis including the CI region. At biochemical failure (BCF), restaging was done with Ga68PSMA-PETCT to establish the patterns of failure. CI-M1a cohort was classified as proximal or distal CI nodal location and studied for outcomes.

RESULTS

Of the 130 patients analyzed, 87 had cN1 and 43 had CI-M1a stage. Median duration of ADT before RT was 7 months and total duration was atleast 24 months. Majority (65%) had Gleason grade group IV-V while 75% had ≥T3 disease. After a median FU of 61 months, BCF in the 2 groups were similar, cN1, 21/87 (24.1%); CI-M1a, 11/43 (25.6%), p=0.86. At BCF, restaging Ga68-PSMA-PET-CT located distant metastases in 20 (63%) of the 32 patients (57% in cN1, and 73% in CI-M1a, p=0.47). Five-year biochemical failure-free survival (cN1; 77.4% and CI-M1a; 70.4%, p=0.43), distant metastasis-free survival (cN1; 86.9% and CI-M1a; 79.4%, p=0.23) and overall survival (cN1 92.6% and CI-M1a 90.1%, p=0.80) were similar in the two groups. Outcomes within CI-M1a were similar for proximal versus distal CI nodal location, 5-year BFFS 73.6% vs 58.6% (p=0.81).

CONCLUSION

Oligometastatic CI-M1a and cN1 prostate cancer patients showed similar outcomes when treated with curative whole pelvic radiotherapy and long-term ADT. The treatment for these 'oligometastatic' patients should be prospectively evaluated and optimized accordingly.

Acute and late toxicity of prostate-only or pelvic SBRT in prostate cancer: A Comparative Study

OBJECTIVE

To compare the urinary and gastrointestinal toxicity with or without the inclusion of pelvic nodal regions in patients treated with extreme hypofractionated stereotactic radiotherapy (SBRT) for prostate cancer.

METHODS

Patients treated with definitive SBRT for non-metastatic adenocarcinoma prostate were identified from prospectively maintained institutional database, and details of radiotherapy volume, dose, acute and late adverse effects were analyzed. Symptoms of acute (within 90 days of completing SBRT) and late gastrointestinal and urinary toxicities were graded using CTCAE version 5.0. Each symptom was scored according to the worst reported grading during treatment and follow-up period. Cumulative toxicity rates between prostate-only SBRT (PO-SBRT) and whole pelvic SBRT (WP-SBRT) were compared using chi-square test.

RESULTS

Total 220 patients were analyzed (PO-SBRT=118, WP-SBRT=102), with a median follow-up of 28 months (IQR 14-40). Most patients had locally advanced disease (PO-SBRT 60% high risk and 40% intermediate risk, WP-SBRT 79% node positive and 21% high risk). Median SBRT dose was 36.25Gy (IQR 35-36.25) to the prostate (EQD2=90.6Gy, a/b=1.5Gy) and simultaneous integrated 25Gy to the pelvis (EQD2=46.3Gy) in five fractions on alternate days. No grade 3-4 acute toxicities were observed except one grade 3 urinary obstruction (PO-SBRT). WP-SBRT was associated with significantly higher acute grade 2 gastrointestinal toxicity (29.4% vs 14.7%, p=0.008) and late grade 2 urinary toxicity (45.6% vs 25.0%, p=0.003). Both the groups had low incidence of late grade 3 toxicities (urinary 2.5%, gastrointestinal 1%).

CONCLUSION

WP-SBRT was associated with significantly higher acute gastrointestinal and late urinary toxicity as compared to PO-SBRT, though overall incidence of severe toxicity was low.

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Evaluation of an automated template-based treatment planning system for radiotherapy of anal, rectal and prostate cancer

•

Automated treatment planning system compared to manual planning.

•

Equivalent plan quality between VMAT manually generated- and IMRT automatically generated plans.

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Evaluation of anal, prostate and rectum treatment plans.

•

Generation of highly consistent IMRT automated plan within 2 to 3.5 min.

Background and purpose

The Ethos system has enabled online adaptive radiotherapy (oART) by implementing an automated treatment planning system (aTPS) for both intensity-modulated radiotherapy (IMRT) and volumetric modulated arc radiotherapy (VMAT) plan creation. The purpose of this study is to evaluate the quality of aTPS plans in the pelvic region.

Material and Methods

Sixty patients with anal (n = 20), rectal (n = 20) or prostate (n = 20) cancer were retrospectively re-planned with the aTPS. Three IMRT (7-, 9- and 12-field) and two VMAT (2 and 3 arc) automatically generated plans (APs) were created per patient. The duration of the automated plan generation was registered. The best IMRT-AP and VMAT-AP for each patient were selected based on target coverage and dose to organs at risk (OARs). The AP quality was analyzed and compared to corresponding clinically accepted and manually generated VMAT plans (MPs) using several clinically relevant dose metrics. Calculation-based pre-treatment plan quality assurance (QA) was performed for all plans.

Results

The median total duration to generate the five APs with the aTPS was 55 min, 39 min and 35 min for anal, prostate and rectal plans, respectively. The target coverage and the OAR sparing were equivalent for IMRT-APs and VMAT-MPs, while VMAT-Aps.

demonstrated lower target dose homogeneity and higher dose to some OARs. Both conformity and homogeneity index were equivalent (rectal) or better (anal and prostate) for IMRT-APs compared to VMAT-MPs. All plans passed the patient-specific QA tolerance limit.

Conclusions

The aTPS generates plans comparable to MPs within a short time-frame which is highly relevant for oART treatments.

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

BACKGROUND

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

METHODS

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

FINDINGS

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

INTERPRETATION

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

FUNDING

National Cancer Institute.

Oligorecurrent nodal prostate cancer: radiotherapy quality assurance of the randomized PEACE V-STORM phase II trial

PURPOSE

Aim of this study is to report the results of the radiotherapy quality assurance program of the PEACE V-STORM randomized phase II trial for pelvic nodal oligorecurrent prostate cancer (PCa).

MATERIAL AND METHODS

A benchmark case (BC) consisting of a postoperative case with 2 nodal recurrences was used for both stereotactic body radiotherapy (SBRT, 30 Gy/3 fx) and whole pelvic radiotherapy (WPRT, 45 Gy/25 fx + SIB boost to 65 Gy).

RESULTS

BC of 24 centers were analyzed. The overall grading for delineation variation of the 1st BC was rated as 'UV' (Unacceptable Variation) or 'AV' (Acceptable Variation) for 1 and 7 centers for SBRT (33%), and 3 and 8 centers for WPRT (46%), respectively. An inadequate upper limit of the WPRT CTV (n=2), a missing delineation of the prostate bed (n=1), and a missing nodal target volume (n=1 for SBRT and WPRT) constituted the observed 'UV'. With the 2nd BC (n=11), the overall delineation review showed 2 and 8 'AV' for SBRT and WPRT, respectively, with no 'UV'. For the plan review of the 2nd BC, all treatment plans were per protocol for WPRT. SBRT plans showed variability in dose normalization (Median D_90% = 30.1 Gy, range 22.9-33.2Gy and 30.6 Gy, range 26.8-34.2Gy for nodes 1 and 2 respectively).

CONCLUSIONS

Up to 46% of protocol deviations were observed in delineation of WPRT for nodal oligorecurrent PCa, while dosimetric results of SBRT showed the greatest disparities between centers. Repeated BC resulted in an improved adherence to the protocol, translating in an overall acceptable contouring and planning compliance rate among participating centers.

Recent Applications of Artificial Intelligence in Radiotherapy: Where We Are and Beyond

In recent decades, artificial intelligence (AI) tools have been applied in many medical fields, opening the possibility of finding novel solutions for managing very complex and multifactorial problems, such as those commonly encountered in radiotherapy (RT). We conducted a PubMed and Scopus search to identify the AI application field in RT limited to the last four years. In total, 1824 original papers were identified, and 921 were analyzed by considering the phase of the RT workflow according to the applied AI approaches. AI permits the processing of large quantities of information, data, and images stored in RT oncology information systems, a process that is not manageable for individuals or groups. AI allows the iterative application of complex tasks in large datasets (e.g., delineating normal tissues or finding optimal planning solutions) and might support the entire community working in the various sectors of RT, as summarized in this overview. AI-based tools are now on the roadmap for RT and have been applied to the entire workflow, mainly for segmentation, the generation of synthetic images, and outcome prediction. Several concerns were raised, including the need for harmonization while overcoming ethical, legal, and skill barriers.

Mapping of Recurrence Sites Following Adjuvant or Salvage Radiotherapy for Prostate Cancer Patients

Introduction

Although salvage and adjuvant radiotherapy (RT) are effective in prostate cancer (PC) patients, 30%–40% of men will have disease progression. The objective was to describe the pattern of recurrence in PC patients with biochemical failure (BF) following postoperative RT.

Methods

We retrospectively analyzed 935 PC patients treated from 2009 to 2019 with adjuvant or salvage RT at the Institut de Cancérologie de l’Ouest. Of these, 205 (22%) developed BF of whom 166 underwent imaging. Patients with identified radiologic failure prior any specific treatment were included to determine the site of relapse categorized as local (L)-only, locoregional (LR), or metastatic (M) recurrence. Main disease characteristics and RT fields were examined in relation to sites of recurrence.

Results

One hundred forty-one patients were identified with 244 sites of failure on imaging. Of these, 108 patients had received RT to the PB alone and 33 RT to the PB and pelvic lymph nodes (PB+PLN). Androgen-deprivation therapy was used concomitantly in 50 patients (35%). The median PSA at imaging was 1.6 ng/ml (range, 0–86.7). In all, 74 patients (52%) had M disease (44% in the PB group and 79% in the PB+PLN group), 61 (43%) had LR failure (52% in the PB alone group and 15% in the PB+PLN group), and six (4%) had L-only failure, at a median of 26.7 months (range, 5–110.3) from RT. Metastases were in extra-pelvic LN (37 (15%)), bones (66 (27%)), and visceral organs (eight (3%)). Fifty-three (48%) of the pelvic LN failures in the PB group would have been encompassed by standard PLN RT volume.

Conclusion

We found that most patients evaluated for BF after postoperative RT recurred outside the RT field. Isolated pelvic nodal failure was rare in those receiving RT to the PB+PLN but accounted for half of failures in those receiving PB alone RT. Imaging directed salvage treatment could be helpful to personalize radiation therapy plan.