ESTRO 2025 - Abstract Book

S2125

Clinical - Urology

ESTRO 2025

Material/Methods: Retrospective study evaluating a group of 86 patients with prostate cancer treated with SBRT between January 2021 and April 2024, 27 of them received hormonal blockade. In order to delimit and optimally protect organs at risk (OARs), the planning CT was performed with bowel preparation and intravesical contrast catheterization. Tumor characteristics, treatment and toxicity were examined. Results: The mean age of the patients at diagnosis was 71.87. risk group: 41 favorable intermediate risk (35.26%), 26 low risk (22.36%), 6 unfavorable intermediate risk (5.16%), 9 low-volume oligometastatic CPHS (6.88%) and 4 high risk (4.3%). The doses received were 36Gy – 37.5Gy applied in 5 or 6 fractions. 57 patients presented grade 1-2 acute urinary toxicity, being self-limited dysuria the most recorded. 6 patients presented acute digestive toxicity, being diarrhea the most common one. Chronic toxicity was observed in 9 patients, the most frequent one was stranguria. We did not observed toxicities ≥ G3. In 14 patients, we could not assesse chronic toxicity because they started treatment in February of this year. Conclusion: Radiation delivery modalities have contributed to increase precision and reduce total treatment time, improving disease control without increasing toxicities. It is a comfortable, non-invasive, outpatient treatment with better results in terms of quality of life compared to conventional radiotherapy.

Keywords: hypofractionation, toxicities, treatment.

References: 1. Moser, M. T., & Biller, A. A. (2020). Stereotactic body radiation therapy (SBRT) for prostate cancer: A review of clinical outcomes and technical considerations . The Cancer Journal, 26(6), 403-411.

2. Liu, X., Wang, J., Zhang, M., et al. (2019). Prostate cancer: Stereotactic body radiation therapy for localized prostate cancer — a systematic review and meta-analysis . Radiotherapy and Oncology, 140, 100-107.

3. Lamb, J. S., & Mendez, L. C. (2021). Outcomes of SBRT for prostate cancer: A decade of experience . Urologic Oncology, 39(7), 463-469.

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Digital Poster Integrating ADC and PSA as predictive factors of treatment response to androgen deprivation therapy and radiotherapy in prostate cancer Victor Duque-Santana 1,2 , Julio Fernandez Mata 3 , Ana Diaz-Gavela 1,2 , Manuel Recio 3 , Marina Peña 1,2 , Luis Leonardo Guerrero 4 , Sofia Sanchez 4 , Fernando Lopez-Campos 5 , Israel J. Thuissard 2 , Cristina Andreu 2 , David Sanz-Rosa 2 , Elia Del Cerro 1,6,2 , Felipe Couñago 7,8 1 Radiation Oncology, H.U. Quironsalud, Madrid, Spain. 2 Department of Medicine, Faculty of Biomedical and Health Sciences, Universidad Europea de Madrid, Madrid, Spain. 3 Radiology, H.U. Quironsalud, Madrid, Spain. 4 Radiation Oncology, H.U. LA Luz, Madrid, Spain. 5 Radiation Oncology, H.U. Ramón y Cajal, Madrid, Spain. 6 Radiation Oncology, H.U. La Luz, Madrid, Spain. 7 Radiation Oncology, H.U. San Francisco de Asis y La Milagrosa, Madrid, Spain. 8 National Chair of Research and Clinical Trials, GenesisCare, Madrid, Spain Purpose/Objective: Previous studies have demonstrated that the Apparent Diffusion Coefficient(ADC) value obtained through multiparametric magnetic resonance imaging(mpMRI) at 6 months post-radiotherapy is a predictive factor for