ESTRO 2025 - Abstract Book

S1993

Clinical - Urology

ESTRO 2025

British Columbia. Eligible patients had histologically confirmed adenocarcinoma of the prostate with unfavorable intermediate, high or very-high risk disease. Patients, enrolled between October 2022 and January 2024, were randomized 1:1 to pelvic CF (40-46Gy/20-23 fractions) or pelvic UHF (25Gy/5 fractions delivered on alternate days). Both regimens were preceded by a single-fraction HDRbb (15Gy) to the prostate with or without proximal seminal vesicles’ inclusion. Toxicities (CTCAEv5) and patient -reported outcomes (IPSS, SHIM, EPIC-26) were recorded longitudinally. Results: At interim, 139 patients had been randomized (UHF n=69, CF n=70) in 10 centers. Overall median follow-up was 338 days (SD 119). ADT treatment, initial PSA, grade group and stage were similar between the 2 arms. There were no reported grade 3 GU toxicities in either arm, and a single grade 3 GI toxicity event was recorded in the UHF cohort. No grade 4 or 5 toxicities were reported in either arm. QoL scores, which included IPSS, SHIM, and EPIC-26, were similar at baseline between treatment arms and displayed no statistical differences at 3- and 6-month follow-ups.