S1186
Clinical - Urology
ESTRO 2026
Integrated Boost (SIB) on prostatic gland with total dose of 65 Gy or 62.5 Gy on prostatic bed in post- operative setting were enrolled in the analysis. Pathologic nodes were identified by pelvic CT and/or MRI, 18F-fluorethylcholine, [68Ga] PSMA-PET-TC. Androgen-deprivation therapy (ADT) was allowed before, during and after RT, for a total recommended ADT period of at least 24 months. Acute and late adverse events (AE) were graded with RTOG and EORTC/RTOG scales, respectively. Local control (LC), Progression Free Survival (PFS), Distant Metastasis Free Survival (DMFS) and Overall Survival (OS) were also evaluated. Results: Twenty-eight PCa patients carrying out 38 nodal lesions entered the analysis. Median age was 68 years (range 54-83) and 15/28 (53.6%) patients had ISUP Grading Group of 4-5. In post-RT restaging exams, only 1/38 (2.6%) infield relapse was seen up to 24 months after study entry. Acute AE were mild as no G ≥ 3 were documented. Grade 3 late AE were generally low with only 1 (3.5%) urinary AE registered, showing as urinary bleeding and severe frequency occurred 7 months after the treatment and 2 gastrointestinal AE (7%) consisting in rectal bleeding after a median time of 13 months. After a median follow-up of 24 months (range 4-109 months), 2 years-LC and OS were 94.4% and 96.3%, whilst 2 years- PFS and DMFS were and 63.6% and 61.5%. Conclusion: For patients with node-positive PCa, definitive RT to the prostate and lymphatic drainage with sequential boost of 12 Gy to the pathologic nodes is a safe and efficient treatment strategy with excellent infield tumor control rates and manageable effects. Prolonged follow-up is needed to confirm this data. Keywords: ProstateCancer, PathologicNodes, RadiosurgeryBoost Dose-response associations in pelvic substructures following Single-Dose Ablative Radiotherapy for prostate cancer: an ABRUPT trial post hoc analysis Stefano Arcangeli 1,2 , Valeria Faccenda 3,1 , Federica Ferrario 2 , Chiara Chissotti 1 , Lorenzo De Sanctis 1 , Giulia Rossano 1 , Elena Arcieri 1 , Riccardo Ray Colciago 1 , Elena De Ponti 3 , Denis Panizza 3,1 1 School of Medicine and Surgery, University of Milan Bicocca, Milan, Italy. 2 Radiation Oncology, Fondazione IRCCS San Gerardo dei Tintori, Monza, Italy. 3 Medical Physics, Fondazione IRCCS San Gerardo dei Tintori, Monza, Italy Digital Poster Highlight 1543
(OR=0.91, p=0.022). After PSM, the arc number was not independently associated with either acute GU or GI G2+. Weighted logistic regression showed that bladder dose metrics did not correlate with acute GU G2+, while rectal dose metrics D5% ≥ 67.5Gy[EQD2], D10% ≥ 58.9Gy[EQD2], D20% ≥ 39.4Gy[EQD2], and D50% ≥ 10.4Gy[EQD2] were significantly associated with increased risk of acute GI G2+ (OR>1.00, p<0.003 for all). Conclusion: Transitioning to a one-arc SBRT technique significantly reduced treatment time without increasing toxicity. Acute GI events were mainly driven by rectal doses, emphasizing the importance of minimizing rectal exposure during planning and delivery. By contrast, acute GU was not dose-related in this cohort, with prostate volume emerging as the main predictor. Long-term follow-up will clarify the impact of single-arc delivery and shorter treatment times on biochemical control. References: Panizza D, Faccenda V, Arcangeli S, De Ponti E. Treatment Optimization in Linac-Based SBRT for Localized Prostate Cancer: A Single-Arc versus Dual- Arc Plan Comparison. Cancers. 2023;16(1):13. Published 2023 Dec 19. doi:10.3390/cancers16010013 Keywords: Prostate SBRT, Arc therapy, Side effects outcomes Boosting the pathologic nodes after whole pelvis in prostate cancer patient: a retrospective analysis. Milena Ferro 1 , Paolo Bonome 1 , Gabriella Macchia 1 , Donato Pezzulla 1 , Marica Ferro 1 , Vincenzo Picardi 1 , Mara Fanelli 1 , Carmela Romano 1 , Savino Cilla 1 , Alessio Giuseppe Morganti 2,3 , Francesco Deodato 1,4 1 Radiation Oncology Unit, Responsible Research Hospital, Campobasso, Italy. 2 Radiation Oncology Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy. 3 Department of Medical and Surgical Sciences, Alma Mater Studiorum University of Bologna, Bologna, Italy. 4 Istituto di Radiologia, Università Cattolica S. Cuore, Roma, Italy Purpose/Objective: To assess safety, feasibility and clinical outcomes of a definitive radiation therapy (RT) consisting in sequential boost of 12 Gy in single fraction after prophylactic irradiation of pelvic nodes in prostate Digital Poster 1530 cancer (PCa) patients. Material/Methods: Patients with N1 PCa treated with a stereotactic radiosurgery boost of pathologic nodes with a single dose of 12 Gy after a prophylactic RT of pelvis with a total dose of 45 Gy in 25 fractions and a Simultaneous
Purpose/Objective: Stereotactic body radiation therapy (SBRT) achieves
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