ESTRO 2025 - Abstract Book

S1918

Clinical - Urology

ESTRO 2025

1025

Digital Poster Acute GU and GI toxicity of Eco guided Clarity© System Stereotactic Body Radiation Therapy for prostate cancer: a single-institutional experience Olga Engel 1 , Alfonso Valcarcel Diaz 1 , M. Dolores De Las Peñas Cabrera 1 , Celia Garcia Torres 1 , Jorge Garcia Guemes 1 , Jose Zapatero Ortuño 1 , Ramon Polo Cezon 2 , Miguel Medina Cespedes 2 , Jose Bayon Llera 2 , Raquel Eugui Martinez 2 , Pilar M. Samper Ots 1 1 Radiation Oncology, University Hospital Rey Juan Carlos, Mostoles, Spain. 2 Medical Physics and Radiation Protection, University Hospital Rey Juan Carlos, Mostoles, Spain Purpose/Objective: A recently published randomized trail confirms non inferiority of Stereotactic body radiation therapy (SBRT) for patients with low and intermediate risk prostate cancer compared to conventionally or moderately hipofractionated regimens with respect to biochemical and clinical failure with significant advantages in time of treatment delivery. However, the need of rectal spacer and urinary catheter placement may result in increased incidence of complications due to invasive nature of these procedures. Intra fraction prostate monitoring with Clarity© system may help to increase treatment accuracy and avoid the need of rectal separation and urethra delimitation.

Material/Methods:

We report results of acute genitourinary (GU) and gastro intestinal (GI) toxicity according to Common Terminology Criteria for Adverse Events scale version 5 in 54 consecutive patients with low and intermediate risk prostate cancer treated in our hospital with Eco guided Clarity© system SBRT with intra fraction prostate monitoring from May 2023 to October 2024. All patients were treated with volumetric modulated arc therapy, the total dose of 36,25 Gy in 5 fractions over 2 weeks was delivered without use a rectal spacer and urinary catheter, thus no dose constrains for urethra were prescribed. The patients’ characteristics are presented in the Table 1 and the SBRT dosimetry