S1191
Clinical - Urology
ESTRO 2026
Digital Poster Highlight 1718 Classical or moderately hypofractionated irradiation of pelvic nodes with prostate boost in high-very high risk prostate cancer: prospective studies. Sergey Nikolaevitch Novikov, Ekaterina Samarceva, Roman Novikov, Nikolay Ilin, Uriy Meregko, Mary Gotovchikova, Olga Ponomareva Radiotherapy, N.N. Petrov Cancer Institute, St Petersburg, Russian Federation Purpose/Objective: To evaluate the long-term efficacy and safety of classical (CF) and moderately hypofractionated (MHF) elective pelvic nodal irradiation (EPLNI) and a prostate boost, combined with androgen deprivation therapy (ADT), in patients with high and very high-risk prostate adenocarcinoma (HVHR PCa). Material/Methods: From 2012 to 2020, 304 patients with HVHR PCa were treated in 2 prospective studies: 88 patients - by MHF EPLNI and 220 – by CF EPLNI. All patients received prostate and seminal vesicles boost: 233 men - by high dose-rate brachytherapy (1 fraction of 15 Gy) and 71 – by stereotactic body radiotherapy (3 fractions of 7 Gy). MHF EPLNI was delivered by VMAT - 13 fractions of 3 Gy five times per week (EQD ₂ α / β = 1.5: 50.1 Gy), CF EPLNI - by 23-25 fractions of 2Gy. Radiation-induced toxicity was assessed according to the RTOG/EORTC grading system and the Common Terminology Criteria for Adverse Events (CTCAE v5.0). Results: The 5-year biochemical recurrence-free survival (BRFS) in the MHF EPLNI group was 83.4%: 88.9% - in high- risk and 80.7% - in very high-risk patients. Local and regional control rates reached 96.4% and 97.6%, respectively. Late grade II and III genito-urinary toxicity rates were 8.3% and 2.4%, while gastrointestinal toxicity rates were 20.2% and 2.4%, respectively.The 5- year BRFS in the classical fractionation EPLNI group was 72.2%: 77.3 % - in high-risk and 70% - in very high- risk patients. Local and regional control rates reached 98.6% and 96.4%, respectively.Late grade II and III genito-urinary toxicity rates were 9.8% and 0%, while gastrointestinal toxicity rates were 8.6% and 5.9%, respectively.5-year overall and cancer-specific survival was similar in MHF and CF groups – 88.1% and 84% (p=0.87%) and 98.8% and 89.5% (p=0.12) respectively. On the contrary, comparison of BRFS in this non-randomized but perfectly balanced studies were in favor of MHF group (p=0.048).
specific antigen level was 0.36 ng/mL (interquartile range, 0.24–0.49 ng/mL). After a median follow-up of 52.6 months, 4-year bPFS rates were 80.1% and 78.1% in the HYPO and CONV arms, respectively (p = 0.88). There were no significant differences in DMFS (91.7% vs. 91.0%) and CSS (100% vs. 100%). The 4-year cumulative incidence of grade ≥ 2 gastrointestinal toxicity was higher in the HYPO arm (8.0% vs. 0.7%, p = 0.003); nevertheless, all cases resolved by the last follow-up. Patient-reported quality-of-life outcomes were comparable.
Conclusion: bPFS was not superior in the HYPO arm at 4 years. However, given the similar oncologic outcomes, toxicity profiles, and quality-of-life measures between both treatment arms, hypofractionated RT may be considered as a viable alternative in a salvage setting. References: King CR. Dose-response of salvage RT post- prostatectomy: systematic review & meta-analysis. Radiother Oncol. 2016;121:199-203.Vale CL et al. Adjuvant vs early salvage RT after prostatectomy: planned systematic review & meta-analysis. Lancet. 2020;396:1422-31.Dearnaley D et al. Conventional vs hypofractionated IMRT for prostate cancer: 5-y CHHiP trial. Lancet Oncol. 2016;17:1047-60.Buyyounouski MK
et al. Hypofractionated vs conventional post- prostatectomy RT: NRG-GU003. JAMA Oncol.
2024;10:584-91.Ranta K et al. Late grade 3–5 toxicities 13 y after hypofractionated post-prostatectomy RT. IJROBP. 2025;123:374-80. Keywords: Biochemical recurrence, Hypofractionation
Made with FlippingBook - Share PDF online