ESTRO 2025 - Abstract Book

S1891

Clinical - Urology

ESTRO 2025

Conclusion: This study represents the current status of the management of HR-prostate cancer in Spain, highlighting the wide variety of radiotherapy treatments as well as the need for national consensus guidelines.

Keywords: High-Risk, Prostate cancer , National Survey

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Digital Poster Prostate Stereotactic Ablative Radiotherapy Dosimetry and Correlations with Acute and Late Toxicity Gokhan Ozyigit, Pervin Hurmuz, Pantea Bayatfard, Burak Tilki, Yagiz Yedekci, Melek Tugce Yilmaz Department of Radiation Oncology, Hacettepe University Faculty of Medicine, Ankara, Turkey Purpose/Objective: SABR is an established treatment modality for prostate cancer; however, there is limited data regarding the dosimetric factors that most effectively predict toxicity [1, 2]. The relationship between prostate volume and toxicity also remains ambiguous. The objective was to identify the dosimetric parameters and prostate volume that most accurately predict the incidence of acute and late gastrointestinal (GI) and genitourinary (GU) toxicity in prostate SABR treatments. Material/Methods: A retrospective analysis was performed on 122 patients who underwent SABR for prostate cancer at our clinic from March 2018 to September 2022, utilizing a 5-fraction SABR regimen. The current treatment plans for these patients were reassessed with our institutional protocols (Hacettepe University [HU-1] and HU-2), along with the dose volume constraints of PACE-B, RTOG 0938, and NRG GU00 (Figure 1). Univariate and multivariate (MVA) logistic regression analyses were performed and dosimetric variables that are significant for toxicity in MVA were further

analyzed using ROC (SPSS version 23.0; IBM, Armonk, NY, USA). Figure 1. Organs at risk dose-volume constraints used in SABR plans