S1246
Clinical - Urology
ESTRO 2026
Poster Discussion 3031
EARLY FINDINGS FROM THE STARR (NCT05455736) TRIAL:STEREOTACTIC SALVAGE RADIOTHERAPY FOR MACROSCOPIC RECURRENCE IN THE PROSTATE BED POST-PROSTATECTOMY Niccolo' Bertini 1 , Giulio Francolini 1 , Michele Aquilano 1 , Vanessa Di Cataldo 1 , Pietro Garlatti 1 , Gabriele Simontacchi 1 , Daniela Greto 1 , Emanuela Olmetto 1 , Icro Meattini 1 , Matteo Mariotti 1 , Olga Ruggieri 2 , Beatrice Bettazzi 1 , Chiara Mattioli 1 , Giulio Frosini 1 , Luisa Caprara 1 , Doruntina Cela 1 , Raffaella Doro 2 , Laura Masi 2 , Saverio Caini 3 , Riccardo Campi 4 , Lorenzo Masieri 5 , Lorenzo Livi 1 1 Radiation Oncology, Azienda Ospedaliero- Universitaria Careggi, Firenze, Italy. 2 Cyberknife Center, Istituto Fiorentino di Cura e Assistenza (IFCA), Firenze, Italy. 3 Cancer Risk Factors and Lifestyle Epidemiology Unit, Institute for Cancer Research, Prevention and Clinical Network, Firenze, Italy. 4 Unit of urological robotic surgery and renal transplantation, Careggi Hospital, Firenze, Italy. 5 Department of Oncologic, Minimally-Invasive Urology and Andrology, Careggi Hospital, University of Florence, Firenze, Italy Purpose/Objective: Salvage radiation therapy (SRT) after radical prostatectomy represents a potentially curative approach for patients with biochemical recurrence (BR). Nevertheless, the presence of metabolically active local recurrence on imaging has been associated with less favourable oncological outcomes. Dose escalation may improve relapse-free survival in this setting. Stereotactic salvage radiotherapy (SSRT) has emerged as a promising technique offering highly conformal dose delivery[1,2]. The STARR trial is a prospective study investigating the safety and efficacy of SSRT in patients with macroscopic prostate bed recurrence. Material/Methods: This trial include patients with biochemical recurrence (PSA > 0.2 ng/mL) following radical prostatectomy, harboring macroscopic prostate bed recurrence detected on PSMA or Choline PET and subsequently confirmed by MRI. Treatment consisted of CyberKnife- based SSRT directed at the macroscopic prostate bed lesion, delivering a total dose of 35 Gy in 5 fractions every other day. Concomitant androgen deprivation therapy (ADT) was not permitted. Complete biochemical response (CBR) and biochemical response (BR) were defined as a post-treatment PSA nadir < 0.2 ng/mL and a > 50% reduction in PSA from baseline at 3 months, respectively. Additional endpoints included biochemical progression-free survival (bPFS), radiological progression-free survival (rPFS), and androgen deprivation therapy–free survival (aPFS).
Graph 1. Box plot of the relative CTV and GTV to receive 95% of the prescribed dose per patient, pre- and post-margin personalisation, with optimal (green line) and mandatory (orange line) objectives. Note that the GTV is only reported where the CTV optimal objective was missed. Conclusion: Whole-bladder MRIgRT with 0.5cm isotropic PTV margins with a personalised approach to margin expansion, is feasible in achieving acceptable CTV coverage providing margin review is performed and appropriate adjustments made. Further evaluation will explore patient-specific variables and dose accumulation analysis in a larger patient cohort. References: [1] Kong, V., Hansen, V. N., & Hafeez, S. (2021). Image- guided Adaptive Radiotherapy for Bladder Cancer. Clinical oncology (Royal College of Radiologists (Great Britain)), 33(6), 350– 368. https://doi.org/10.1016/j.clon.2021.03.023[2] Hunt, A., Hanson, I., Dunlop, A., Barnes, H., Bower, L., Chick, J, et al. (2020). Feasibility of magnetic resonance guided radiotherapy for the treatment of bladder cancer. Clinical and translational radiation oncology, 25, 46–51. https://doi.org/10.1016/j.ctro.2020.09.002 Keywords: Bladder, adaptive, personalised margins
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