To evaluate dose-volume histogram metrics and preliminary toxicity of prostate cancer (PC) patients affected by postoperative locoregional relapse treated with moderately hypofractionated salvage radiotherapy (sRT) using AI-assisted daily adaptive RT.
This is a prospective observational study (4181CESC, NCT05884632) on adaptive 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™ system which generates two plans: scheduled and adapted. The scheduled plan includes 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 select the preferred one for treatment. This is an interim analysis reporting on DVH metrics (scheduled versus adapted plan) and toxicity outcome.
The results of the first 840 treatment fractions in 42 patients are reported. Sixteen (37.2%) had biochemical relapse only, while 27 (62.8%) had macroscopic relapse. We reported a significant improvement between scheduled and adapted plan for rectum V52.8Gy (16.9% versus 12.8%); p ≤0.0001), rectum Dmean per fraction (1.54Gy/fraction versus 1.42 Gy/fraction; p ≤0.0001), prostate bed PTV95%, (92.1% versus 98.5%; p ≤0.0001), pelvis PTV95% (<0.0001), pelvis PTV107% (<0.0001), and bowel Dmax (<0.0001). There was no difference for prostate bed PTV107%, bladder Dmean, and bladder V40.8Gy. Grade 2 GI toxicity (overall) was 4.8%. Grade 2 GU toxicity (overall) was 9.5% of cases. In the univariate analysis, the only factor associated with diarrhea onset was the inclusion of the pelvis (p = 0.002). There was no difference between treatment dose and toxicity.
Preliminary data seems to show minimal acute toxicity. A longer follow up is needed to confirm these data and evaluate late toxicity.
Clinical and translational radiation oncology. 2026 Jul 17*** epublish ***
Luca Nicosia, Riccardo Filippo Borgese, Nicola Bianchi, Carolina Orsatti, Andrea Gaetano Allegra, Jacopo Balduzzi, Margherita Corsi, Chiara De-Colle, Antonio De Simone, Matilde Fiorini, Niccolò Giaj-Levra, Davide Gurrera, Cristina Mazzi, Stefania Naccarato, Edoardo Pastorello, Francesco Ricchetti, Michele Rigo, Andrea Romei, Gianluisa Sicignano, Gloria Guardia, Patricia Salgado Gonzàles, Ruggero Ruggieri, Filippo Alongi
Advanced Radiation Oncology Department, IRCCS Sacro Cuore Don Calabria Hospital Cancer Care Center Negrar di Valpolicella, Italy., Medical Physics Unit, IRCCS Sacro Cuore Don Calabria Hospital Cancer Care Center Negrar di Valpolicella, Italy., Department of Radiation Oncology, Hospital Universitario 12 de Octubre, Madrid, Spain., Oncologia Radioterapàpica, Hospital Universitario Fundaciòn Jimènes Dìa, Madrid, Spain.