ESTRO 2025 - Abstract Book

S1965

Clinical - Urology

ESTRO 2025

A multi-institutional YAU RCC working group dataset was used to select patients with a single renal mass who underwent surgery at one referral center from 2015 to 2022. All patients included in this study presented a preoperative cross-sectional imaging CT scans and were classified among the PADUA score and stratified in 3 groups: low (PADUA 6-7), intermediate (8-9) and high (10-13). Thirty patients (10 for each category) were randomly selected for the current analysis. Diagnostic CT was used as planning CT to simulate a Cyberknife R SBRT plan for a total dose of 26 Gy or 42 Gy in one or three fractions depending on lesions < or > 4cm respectively. Fiducials positioning within the treated lesions was simulated to consider the intrafraction respiratory movements and tumor tracking. A plan was judged feasible if all coverage requests and OAR constraints according FASTRACK II protocol were respected. Results: Sixteen treatment plans were included in the current analysis, 9, 2 and 5 within the low, intermediate or high PADUA score groups, respectively. Of these, 3 plans (1 in the low 1 in the intermediate and 1 in the high groups) were judged unfeasible due to failure to comply with pre-defined small bowel constraints. All other treatment plans fulfilled the coverage and dose constraints requests and were judged feasible, including 4 patients with PADUA score > 10. Conclusion: SBRT was assessed potentially feasible for all lesions with higher PADUA scores, both from an efficacy and safety point of view. This suggests that critical issues of surgery and SBRT may be complementary and SBRT could be a viable approach for patients with higher PADUA scores who may be suboptimal candidates for nephron sparing surgery outside high referral surgical centers.

Keywords: Kidney cancer; SBRT;surgery

References: 1. Siva S, Bressel M, Sidhom M, et al. Stereotactic ablative body radiotherapy for primary kidney cancer (TROG 15.03 FASTRACK II): a non-randomised phase 2 trial. Lancet Oncol. 2024;25(3):308-31 2. Bertolo R, Francolini G, Bukavina L. Functional Outcomes of Stereotactic Ablative Radiotherapy: There Is Room for Improvement. Eur Urol Oncol. Published online July 30, 2024. doi:10.1016/j.euo.2024.07.004

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Poster Discussion Early results from a trial on stereotactic salvage radiotherapy for macroscopic prostate bed recurrence after prostatectomy: STARR (NCT05455736) Niccolo' Bertini 1 , Giulio Francolini 1 , Vanessa Di Cataldo 1 , Pietro Garlatti 1 , Michele Aquilano 2 , Luca Burchini 1 , Giulio Frosini 1 , Cecilia Petruccioli 1 , Laura Masi 2 , Raffaela Doro 2 , Gabriele Simontacchi 1 , Mauro Loi 1 , Lorenzo Livi 1 1 Radiation Oncology, Azienda Ospedaliero-Universitaria Careggi, Firenze, Italy. 2 Cyberknife Center, Istituto Fiorentino di Cura e Assistenza (IFCA), Firenze, Italy Purpose/Objective: Salvage radiation therapy (SRT) after radical prostatectomy offers a curative treatment option for biochemical recurrence (BR). However, positive metabolic imaging indicating local recurrence is associated with poorer outcomes. Escalating the radiation dose may improve relapse-free survival. Stereotactic salvage radiotherapy (SSRT) has emerged as a promising approach[1-2]. STARR trial (STereotactic sAlvage Radiotherapy for macroscopic prostate bed Recurrence after prostatectomy — NCT05455736) is a prospective study evaluating patients with macroscopic prostate bed recurrence undergoing stereotactic radiotherapy. This report presents an early analysis of the first cohort of patients enrolled in this ongoing trial. Material/Methods: