ESTRO 2024 - Abstract Book

S2592

Clinical - Urology

ESTRO 2024

Keywords: ultra hypofractionated radiotherapy

2944

Digital Poster

Real-world analysis of treatment related toxicity following prostate SBRT

Chiara Chissotti 1,2 , Federica Ferrario 1,2 , Valeria Faccenda 3 , Raffella Lucchini 1,2 , Maria Belmonte 1,2 , Giorgio Purrello 1,2 , Denis Panizza 1,3 , Stefano Arcangeli 1,2 1 University of Milan Bicocca, School of Medicine and Surgery, Milano, Italy. 2 Fondazione IRCCS San Gerardo dei Tintori, Department of Radiation Oncology, Monza, Italy. 3 Fondazione IRCCS San Gerardo dei Tintori, Department of Medical Physics, Monza, Italy

Purpose/Objective:

Hypofractionated radiotherapy for prostate cancer (PCa) has gained increased attention due to its proposed high radiation-fraction sensitivity. Recent reports from studies comparing Stereotactic body radiation therapy (SBRT) and moderately hypofractionated and/or conventionally fractionated radiotherapy support the clinical use of SBRT due to his non-inferiority compared to longer schedules and similar toxicity profile. The aim of this retrospective monoinstitutional analysis is to assess treatment-related toxicity of radical SBRT, considering different parameters.

Material/Methods:

In our institution patients with imaging- and biopsy-proven organ-confined PCa, irrespective of the risk class and prostate volume, have been treated with linac-based SBRT to the prostate and seminal vesicles, delivered with Volumetric Modulated Arc Therapy (VMAT) every other day. All patients were immobilized in the supine position, with empty rectum and bladder filled by drinking 500 mL of still water to assess anatomical reproducibility and mitigate the organ motion. Two different fractionation schedules were used: 36.25 Gy in five fractions (EQD2 1.5 = 90.6 Gy) and 42.7 Gy in seven fractions (EQD2 1.5 = 92.7 Gy). Androgen deprivation therapy (ADT) was prescribed as guidelines indicates and/or physician discretion due to clinical reasons. Alpha-blockers were prescribed at the beginning of the radiation treatment to prevent side effects to all patients. Acute and maximum late toxicity was assessed using CTCAE v.5 scale; urinary patient-reported outcomes and biochemical control have been evaluated at baseline and at every follow-up, through International Prostatic Symptoms Score (IPSS) questionnaires and PSA serum levels, respectively.

A logistic regression analysis was performed to evaluate potential associations between specific patient-related, tumor-related or treatment-related factors and a worsening of clinical outcomes in terms of toxicity.

Results: