ESTRO 2025 - Abstract Book

S1978

Clinical - Urology

ESTRO 2025

difference in bPFS was observed between BRCA-positive and BRCA-negative patients (HR 0.93, p=0.06). However, BRCA-untested patients had a significantly lower risk of biochemical progression (HR 0.58, p=0.02). The addition of SBRT in the experimental arm showed a clear benefit in terms of bPFS in both the BRCA-negative and BRCA untested groups, with HRs of 0.37 (95% CI 0.19-0.73) and 0.50 (95% CI 0.14-0.76), respectively. In the BRCA-positive group, the results were inconclusive due to the small sample size (HR 0.50, 95% CI 0.09-2.89).

Conclusion: In a selected cohort of omCRPC patients enrolled in a prospective trial, the benefit of SBRT was confirmed for those who were BRCA negative or untested. However, larger studies involving BRCA-positive omCRPC patients receiving SBRT are necessary to validate these findings in this subgroup.

Keywords: PROSTATE CANCER, SBRT, BRCA mutation

1908

Digital Poster Impact of hypofractionated prostate cancer radiotherapy on erectile dysfunction and its correlation with radiation dose to the erectile structures. Raouia Ben Amor 1,2 , Syrine Lahiouel 1,2 , Roua Toumi 1 , Zeineb Naimi 1,2 , Ghada Bouguerra 1 , Awatef Hamdoun 1 , Lotfi Kochbati 1,2 1 Radiation Oncology, Abderrahmen Mami Hospital, Ariana, Tunisia. 2 Faculty of Medicine of Tunis, Tunis El Manar University, Tunis, Tunisia Purpose/Objective: We aimed to assess the correlation between the dose to the penile bulb(PB), internal pudendal arteries (IPA),and crura with the development of erectile dysfunction(ED) after hypofractionated prostate radiation therapy (HFPRT). Material/Methods: Forty-four patients underwent HFPRT using a VMAT technique, receiving a total dose of 60 Gy in 20 fractions. Androgen deprivation therapy (ADT) was administered for 6 months to 20 patients (45%).MRI and CT images were fused for erectile structures delineation, including the PB, IPA, and crura. No specific dose-volume objectives were applied to these structures. Erectile dysfunction (ED+) was defined as the development of grade 2 to 3 adverse events according to the CTCAE version 5.0. The mean dose (Dmean) and near-maximum dose (D2%) to each erectile structure were analyzed. ANOVA and chi-square tests were used to assess the correlation between radiation doses delivered to the PB, crura, and IPA, and the development of ED+. Quality of life was evaluated using the EORTC QLQ PR25 questionnaire, and results were reported.