ESTRO 2025 - Abstract Book

S1994

Clinical - Urology

ESTRO 2025

Conclusion: The PCS-XI trial interim analysis indicates that pelvic UHF IMRT/VMAT combined with HDRbb is safe and well tolerated in the short term in patients with prostate cancer requiring pelvic nodal radiation (risk ≥15% of nodal involvement). These findings support the use of UHF regimen as a potentially safe alternative to conventional fractionation, while offering significantly shorter treatment duration. Ongoing follow-up will provide further insight into long-term toxicity, efficacy and economic outcomes.

Keywords: HDR, brachytherapy, hypofractionation

References: 1 Widmark, A. et al . Ultra-hypofractionated versus conventionally fractionated radiotherapy for prostate cancer: 5 year outcomes of the HYPO-RT-PC randomised, non-inferiority, phase 3 trial. The Lancet (2019) 2 Fowler, JF. et al . Is the α/β Ratio for Prostate Tumours Really Low and Does It Vary with the Level of Risk at Diagnosis? Anticancer Res. (2013) 3 Kraus,RD. et al. Benefits of Adopting Hypofractionated Radiotherapy as a Standard of Care in Low-and Middle Income Countries. JCO Glob. Onco. (2022) 4 Mendez, LC. et al . Is Ultrahypofractionated Whole Pelvis Radiation Therapy (WPRT) as Well Tolerated as Conventionally Fractionated WPRT in Patients With Prostate Cancer? Early Results From the HOPE Trial. Int. J. Rad.Onco. Bio. Phys. (2024)

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Poster Discussion Daily Adaptive RadioTherapy in Postoperative HypofrActionated Salvage radiothERapy for prostate cancer patients (DART-PHASER): early results Luca Nicosia 1 , Carolina Orsatti 1 , Riccardo Filippo Borgese 1 , Margherita Corsi 2 , Andrea Gaetano Allegra 1 , Nicola Bianchi 1 , Chiara De-Colle 1 , Antonio De Simone 1 , Niccolò Giaj-Levra 1 , Davide Gurrera 1 , Stefania Naccarato 1 , Edoardo Pastorello 1 , Francesco Ricchetti 1 , Michele Rigo 1 , Andrea Romei 1 , Gianluisa Sicignano 1 , Ruggiero Ruggeri 1 , Filippo Alongi 1,3 1 Department of Advanced Radiation Oncology, IRCCS Sacro Cuore Don Calabria, Negrar di Valpolicella, Italy. 2 Medical Physics Unit, IRCCS Ospedale Sacro Cuore Don Calabria, Negrar di Valpolicella, Italy. 3 University of Brescia, University of Brescia, Brescia, Italy Purpose/Objective: Salvage radiotherapy (sRT) is commonly used for locoregional prostate cancer (PC) relapse. Modern technology like adaptive RT can help in improving safety and accuracy of those treatments. Ethos system uses daily imaging and artificial intelligence to adjust treatment plans based on daily anatomy. This might set a new standard in the setting of sRT, balancing efficacy with reduced toxicity. We report the preliminary toxicity results of moderately hypofractionated adaptive sRT. hypofractionated sRT in PC. Eligible patients (up to 80 years old, post-prostatectomy, PSMA-PET-CT confirmed M0) received 20 daily fractions up to 59 Gy for macroscopic relapse and 55 Gy for biochemical-only relapse. When indicated, pelvis was included with a dose of 45 Gy. The treatment was administered using Ethos, an AI-powered system that adjusts treatment plans based on daily anatomical changes. Ethos system generates two available plans: the scheduled and the adapted. The scheduled plan consists on a dose recalculation on daily synthetic CT (generated from daily CBCT). The adapted plan consists on a reoptimization based on the daily anatomy. The user then selects either the scheduled or adaptive plan for treatment. Primary endpoint was acute gastrointestinal (GI) Material/Methods: This is a prospective observational study (NCT05884632) evaluating the safety and efficacy of adaptive