ESTRO 2025 - Abstract Book

S1915

Clinical - Urology

ESTRO 2025

Brescia, Italy. 9 Department of Health Sciences (DISSAL), University of Genoa, Genoa, Italy. 10 Radiation oncology unit, IRCCS Ospedale Policlinico San Martino, Genoa, Italy. 11 adiation Oncology Department, Bellaria Hospital, AUSL of Bologna, Bologna, Italy. 12 Radiotherapy Department, Humanitas Gavazzeni hospital, Bergamo, Italy. 13 Radiation Oncology Unit, Clinical Department, National Center for Oncological Hadrontherapy (CNAO), Pavia, Italy. 14 Radiotherapy Department, Santa Maria Goretti Hospital, Latina, Italy. 15 Dipartimento di Scienze biomediche e odontoiatriche e delle immagini morfologiche e funzionali, Università di Messina, Messina, Italy. 16 Department of Radiation Oncology, Istituto Nazionale Tumori-IRCCS-Fondazione G. Pascale, Napoli, Italy. 17 Cancer Risk Factors and Lifestyle Epidemiology Unit, Institute for Cancer Research, Prevention and Clinical Network (ISPRO), Florence, Italy. 18 Cyberknife Center, Istituto Fiorentino di Cura e Assistenza, Florence, Italy Purpose/Objective: Treatment options for recurrence after postoperative or definitive radiotherapy (RT) for prostate cancer include androgen deprivation therapy (ADT) or local salvage treatment comprehensive of surgery, focal therapy or re irradiation [1]. Nonetheless, promising treatment outcomes have been shown after local salvage techniques [2], making these options appealing if compared to the significant quality of life impact given by lifelong ADT. Italian Association for Radiation Oncology (AIRO) endorsed a multicentric registry aiming to assess safety and efficacy in a large cohort of patients undergoing re-irradiation in this scenario. Material/Methods: RE-START registry included retrospectively collected data about patients treated with definitive or postoperative radiotherapy and undergoing re-irradiation in 5 centers in Italy and Poland for local relapse (e.g intraprostatic or prostate bed macroscopic recurrence). Relapse was detected through PET CT or Magnetic resonance imaging, and main exclusion criteria were presence of metastatic or regional disease or a follow up shorter than 6 months after re-irradiation. All treatment schedules providing at least 5 Gy per fraction were allowed. Primary endpoint of the analysis is rate of acute and late gastrointestinal (GI) and genitourinary (GU) adverse events according to Common Terminology Criteria for Adverse Events (CTCAE). Results: Overall, 433 patients were currently analyzed. Of these, 27, 159 and 247 underwent re-irradiation through brachytherapy, robotic stereotactic RT or Intensity modulated RT, respectively. Concomitant ADT was administered in 54,7% of cases. Acute GI G1, G2 and G3 toxicity was reported in 7.6, 1.9 and 0.2% of cases. Acute GU G1, G2 and G3 toxicity were reported in 26.3, 9 and 0.5% of patients. After a median follow up of 54 months (95%CI 26-78), late Grade >3 GU and GI toxicity were reported only in 8.5% and 2.1% of patients, respectively. Median biochemical relapse free, metastasis free and overall survival (BRFS, MFS and OS) were 34 months (IQR 15-98), 118 months (IQR 40-NR) and 109 months (IQR 64-142), respectively. At univariate analysis, BRFS was significantly associated with use of PSMA (HR 0.6, 95%CI 0.3-0.99) and time to recurrence <36 months (HR 1.6, 95%CI 1.1-2.1). MFS and OS were significantly worse in patients treated in castration resistant setting (HR 1.7, 95%CI 1-3 and HR 2.2, 95%CI 1.2-3.9). Conclusion: Reirradiation was safe and provided promising oncological outcomes in a large multicentric series after 4.5 years of median follow up. Use of PSMA imaging and early treatment (e.g avoiding development of castration resistance), may significantly improve treatment outcomes.

Keywords: Reirradiation, Prostate cancer, AIRO

References:

1. Ingrosso G. Nonsurgical Salvage Local Therapies for Radiorecurrent Prostate Cancer: A Systematic Review and Meta-analysis. Eur Urol Oncol. 2020 Apr;3(2):183-197. 2. Valle LF. A Systematic Review and Meta-analysis of Local Salvage Therapies After Radiotherapy for Prostate Cancer (MASTER). Eur Urol. 2021 Sep;80(3):280-292.