ESTRO 2025 - Abstract Book

S1991

Clinical - Urology

ESTRO 2025

PCa and treated between July 2023 and April 2024 with Hypo-sRT schedule, consisting in 26 daily fx with a simultaneous dose-escalation 67,6 Gy to MRI+ recurrence and dose-descalation 57,2 Gy on negative prostate bed volume. All patients were re-staged at biochemical recurrence with NGI (PSMA PET-TC and pelvic mpMRI) prior to sRT to assess macroscopic recurrence and exclude lymph nodal and distant metastases. No ADT was administered. ESTRO-ACROP contouring guidelines were used to delineate OARs and target volumes. Simulation mpMRI was merged to planning CT to contour local recurrence (GTV67,6) and improving delineation of prostate bed volume (CTV57,2). Isotropic expansion of 6mm (5mm posterior) from GTV67.6 and CTV57,2 created PTV67,6 and PTV57,2, respectively. Treatment was prescribed to median PTVs dose, planned using VMAT technique and delivered on LINAC. Daily CBCTs were used as image-guidance. Acute genitourinary (GU) and gastrointestinal (GI) toxicities were graded using the Common Terminology Criteria for Adverse Events, version 5.0.

Results: Median follow-up was 8 months. Four patients had ISUP GG II and 4 GG III. One, 1, 4 and 2 patients were TNM pT2a, pT2b, pT2c and pT3a respectively. Three pts had positive surgical margins. All patients were pN0. Median PSA before sRT was 0,32 ng/ml and median PSADT 10 months. Median recurrence diameter was 12mm. Recurrences were located at VUA and retrovescical in 5 and 4 pts, respectively. No acute G3-4 GU and GI toxicities were reported.