S1214
Clinical - Urology
ESTRO 2026
(intermediate- and high-risk) in five fractions. Androgen deprivation therapy (ADT) was allowed when clinically indicated. Planning target volumes (PTVs) were generated with a 2-mm isotropic margin. All patients completed the prescribed treatment. Acute and late toxicities were evaluated according to the Common Terminology Criteria for Adverse Events (CTCAE v5.0). Results: A total of 100 patients were enrolled and treated between July 2023 and May 2025. The median age was 76 years (range, 52–91). Risk distribution was 29% low- risk, 57% intermediate-risk, and 14% high-risk. The median follow-up was 12.4 months. Forty-eight percent of patients received androgen deprivation therapy (ADT). The median prostate volume was 47 cc (range, 17–154 cc). The median PSA at diagnosis was 6.11 ng/mL (range, 0.9–47.3), which decreased to 0.64 ng/mL (range, 0.01–2.6) at 12.4 months post- treatment. Genitourinary (GU) toxicities of Grade 1–2 were reported in 17% of patients at 3 months, 4% at 6 months, and 0% at 1 year. Gastrointestinal (GI) toxicities of Grade 1–2 were observed in 1% of patients at 3 months, 3% at 6 months, and 0% at 1 year. The Mann–Whitney U test was used to evaluate correlations between toxicity and variables including age, prostate volume, dose, and prior urological procedures; no statistically significant associations were identified. No Grade ≥ 3 adverse events or treatment-related deaths occurred during the study period. Conclusion: This prospective analysis demonstrates that CTCAE- defined toxicities associated with adaptive MR-guided SBRT were minimal and consistent with previously reported data. SBRT with MRgRT was safe and well tolerated, showing low rates of both GU and GI toxicity. Longer follow-up is required to assess biochemical control outcomes. References: Tocco BR, Kishan AU, Ma TM, Kerkmeijer LGW, Tree AC. MR-Guided Radiotherapy for Prostate Cancer. Front Oncol. 2020;10:616291. Published 2020 Dec 9. doi:10.3389/fonc.2020.616291 Keywords: SBRT, prostate cancer, MRgRT Does Simultaneous Integrated Boost Improve Outcomes in Unfavorable Intermediate-Risk Prostate Cancer? Cem Onal 1,2 , Aysenur Elmali 2 , Birhan Demirhan 3 , Ertugrul Senturk 4 , Petek Erpolat 4 , Ozan Cem Guler 1 1 Department of Radiation Oncology, Baskent University Faculty of Medicine Adana Dr. Turgut Noyan Research and Treatment Center, Adana, Turkey. Digital Poster Highlight 2145
Digital Poster Highlight 2123
Safety and Feasibility of 0.35T MR-Guided Adaptive SBRT in Localized Prostate Cancer: A Prospective Analysis Abrahams Ocanto 1,2 , Macarena Teja 1,2 , María González 1,2 , Castalia Fernández 1,2 , Lisselott Torres 1,2 , Gloria Guardia 1,2 , Daniela Gonsalves 1,2 , Gloria Sánchez 3 , Álvaro Gaona 4 , Tomás González 5 , Claudia Colom 6 , Leticia Del Campo 7 , Jasuani Bravo 8 , Fernando López-Campos 2,9 , Miren Gaztañaga 2,10 , Maia Dzhugashvili 2 , Escarlata López 11 , Luis Glaría 1,12 , Raul Hernanz 1,9 , Isabel Garrido 13 , Felipe Couñago 14,15 1 Radiation Oncology, San Francisco de Asís University Hospital, Madrid, Spain. 2 Radiation Oncology, Vithas La Milagrosa University Hospital, Madrid, Spain. 3 Radiation Oncology, Blua Sanitas Valdebebas Hospital, Madrid, Spain. 4 Radiation Oncology, Santa Bárbara Hospital, Soria, Spain. 5 Radiation Oncology, Centro Médico ABC, Ciudad de México, Mexico. 6 Radiation Oncology, Miguel Servet University Hospital, Madrid, Spain. 7 Radiation Oncology, Fundación Jiménez Díaz University Hospital, Madrid, Spain. 8 Radiation Oncology, Instituto Nacional de Cancerología, México, Mexico. 9 Radiation Oncology, Ramón y Cajal University Hospital, Madrid, Spain. 10 Radiation Oncology, Clínico San Carlos University Hospital, Madrid, Spain. 11 Radiation Oncology, GenesisCare Granada, Granada, Spain. 12 Radiation Oncology, La Paz University Hospital, Madrid, Spain. 13 Radiation Oncology, Centro de Protonterapia Quirónsalud, Madrid, Spain. 14 National Director, GenesiCare Spain, Madrid, Spain. 15 Department of Medicine, School of Medicine, Health and Sport, European University of Madrid, Madrid, Spain Purpose/Objective: External beam radiotherapy is a well-established treatment for localized prostate cancer. Recent evidence supports hypofractionation, and more recently, ultra-hypofractionated radiotherapy delivered via stereotactic body radiotherapy (SBRT) has emerged as a preferred approach due to its efficacy, shorter treatment course, and favorable tolerance profile. This technique, however, relies heavily on advanced technology and imaging capabilities, including reduced treatment margins made possible by MR-guided radiotherapy (MRgRT). This study evaluates the tolerability of SBRT in patients with localized prostate cancer treated using a 0.35T Patients with localized prostate cancer (low-, intermediate-, and high-risk) were enrolled in a prospective trial (Protocol No. 5289). Treatment consisted of adaptive SBRT delivered with MR-LINAC to a total dose of 36.25 Gy (low-risk) or 40 Gy MR-LINAC system. Material/Methods:
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