ESTRO 2024 - Abstract Book

S2475

Clinical - Urology

ESTRO 2024

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Prostate Cancer ultra-hypofractionation: single-center late tolerance analysis, two-years data

Ilaria Bonavero 1 , Giuseppe Carlo Iorio 1 , Sara Bartoncini 1 , Elena Gallio 2 , Diego Bongiovanni 1 , Sara Gaspari 1 , Valeria Chiofalo 3 , Cristiano Grossi 1 , Fabio Menegatti 1 , Edoardo Gozzelino 1 , Erica Cuffini 3 , Giuliana Petruzzelli 1 , Marzia Cerrato 1 , Bruna Lo Zito 1 , Chiara Casale 1 , Francesca Catena 1 , Eulalie Joelle Tondji Ngassam 1 , Mario Levis 1 , Parise Ramona 1 , Umberto Ricardi 1 1 University of Turin, Department of Oncology, Turin, Italy. 2 University of Turin, Department of Medical Physics, Turin, Italy. 3 University of Turin, Department of Oncology, Turin, Japan

Purpose/Objective:

Late tolerance evaluation of ultra-hypofractionated RT for localised (low- to high-risk) prostate cancer (PCa).

Material/Methods:

This late toxicity analysis pertains to a single-center cohort of patients (pts) treated with LINAC-based VMAT ultra hypofractionation (42.7 Gy/7 fractions every other day; 15-19 days). The treatment was delivered with daily IGRT (Cone-Beam CT). No fiducials nor spacers were employed. The CTV – PTV margin was 7 mm (5 mm towards the rectum). The CTV was defined as the prostate only for low-risk (LR) pts. CTV included proximal seminal vesicles (SVs) in intermediate-risk PCa and distal SVs for high-risk pts (HR). Whole SVs were included in the case of cT3b. Hormonal therapy prescription (HT) was at the physician's discretion in unfavorable-intermediate PCa (UIR) and mandatory in HR. Genitourinary (GU) and gastrointestinal (GI) toxicity were scored according to RTOG. The IPSS (≤12 or >12) was also assessed. Timepoints of the late toxicity report were: 6-, 12-, 18-, and 24-months from the RT end. Additionally, a statistical analysis (logistic regression analysis) was performed to identify the predictive risk factors of late (6- to 24- months from the RT end) GU G2+ events. Among the investigated factors: risk-group, previous TURP, baseline alpha- blocker administration, baseline IPSS value, prostate volume (≤ or > 80cc), HT administration, overall treatment time (OTT, ≤17 or >17 days), bladder V37 Gy (≤10cc, ≤15cc, ≤20cc, >20cc), GU acute toxicity.

Results: