S1306
Clinical - Urology
ESTRO 2026
gastrointestinal (GI) treatment-related events. Secondary endpoints included biochemical recurrence-free survival (BRFS), clinical progression- free survival (CPFS), and dosimetry to organs at risk (OARs). Results: From May 2013 to February 2025, 21 and 8 patients received a third RT course to a radiologicaly-detectable intraprostatic or prostate-bed recurrence, respectively. Androgen deprivation therapy (ADT) was not routinely used; only ten patients received concurrent ADT. Four patients were lost at the first FUP clinical visit, but were included in the study for the dosimetric analysis. Of the remaining 25 patients, median FUP was 40.0 months (IQR: 13.9 – 65.5). Seven grade 3 and 1 grade 4 GU events were recorded. One grade 3 GI event was observed. Median BRFS was 19.3 months (IQR: 12.7 – 30.8). Median CPFS was 27.1 months (IQR: 13.9 – 40.0). At the time of the analysis, nine patients (36%) are considered disease-free.
Conclusion: This unique study shows that a third RT course can be proposed in experienced centers as an effective salvage therapy, potentially prolonging relapse-free survival and ADT-free interval. PT was associated with a lower incidence of GU and GI events, and with a dosimetric advantage on rectum and bladder. Additional investigations are warranted to comprehensively ascertain the optimal dose prescription and dosimetric constraints for OARs. References: 1. DOI: 10.1016/S0167-8140(25)03062-2 Keywords: reirradiation, third RT, prostate cancer Digital Poster 4811 Stereotactic body radiation therapy for intermediate-risk prostate cancer: efficacy and toxicity. María Dolores Espinosa Cuesta 1 , Isabel Alvira Ortiz 1 , Jose Antonio Domínguez Rullán 1 , Julen Azcona Martín 1 , Ignacio Maria Gómez Paloma 1 , Adrián Durango Méndez 1 , Belén Santafe Mengual 1 , María Etcheverry Dadin 1 , David Sevillano Martínez 2 , Juan David García Fuentes 2 , Carmen Vallejo Ocaña 1 , Fernando López Campos 1 , Maria Teresa Muñoz Miguelañez 1 , Patricia Martín Nieto 1 , Sonsoles Sancho García 1 , Asunción Hervás Morón 1 1 Radiation Oncology, Ramón y Cajal University Hospital, Madrid, Spain. 2 Radiophysics, Ramón y Cajal University Hospital, Madrid, Spain
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