ESTRO 2025 - Abstract Book

S382

Brachytherapy - Urology

ESTRO 2025

Material/Methods: We conducted a retrospective analysis of a series of patients with Re-PCa treated with HDR-BT in our centre. Patients were staged following biochemical failure (PSA >2 ng/mL) with choline PET-CT, MRI, and a biopsy-proven local relapse. Salvage treatment consisted of concomitant 6 months of androgen deprivation therapy (ADT) and whole gland HDR BT in 4 fractions of 8 Gy or, alternatively, 2 fractions of 13,5 Gy. Survival analysis was performed using Kaplan Meier model with SPSS v25. Acute or chronic toxicity were rated according to CTCAEv5.0. Results: Between 2013 and 2023, 63 patients were treated with salvage HDR-BT. The characteristics of the cohort are shown in table 1 . Median follow-up was 44 months (6-131). A total of 96,3% of patients were staged with PET-CT, and 60,32% with MRI. Overall, 79,37% of patients received ADT, including short course ADT (6 months) in 61,9% and long course ADT (30 months) in 17,46%. The HDR-BT was performed with a median of 18 needles (6-24). Median dosimetric prostate parameters were D90= 106,25% (8,5 Gy), V100 =96,46% and V150 =25,78%. Median dosimetric OAR parameters were D1cc-Urethra= 111,26%, D1cc-Bladder= 72,5%, D1cc-Rectum= 53,77%, and D2cc-Rectum= 52.04%. The 3- and 5-years biochemical survival, metastases-free survival, disease free survival and overall survival were 78,7% and 70,7%; 92,3% and 85%; 82,1% and 74,5%; and 96,1% and 91,5% respectively. The 5-year disease-specific survival was 95,2%. Overall grade 3-4 (G3-4) toxicity was 22%. Acute G3-4 genitourinary (GU) toxicity was 6,3%, and acute G3-4 gastrointestinal (GI) toxicity was 0%. Chronic G3-4 GU toxicity was 15,9% and chronic G3-4 GI toxicity was 4,8%. Toxicity analysis is detailed in figure 1 .