ESTRO 2025 - Abstract Book

S2088

Clinical - Urology

ESTRO 2025

Conclusion: A third RT course can be proposed as a possible salvage therapy for PCa local recurrence, further prolonging the relapse-free survival. However, additional studies are necessary to fully evaluate the most suitable and tolerable dose prescription and consequently dosimetric constraints to rectum and bladder.

Keywords: re-irradiation; prostate cancer; third RT

References: 1. Abusaris H, Hoogeman M, Nuyttens JJ. Re-irradiation: outcome, cumulative dose and toxicity in patients retreated with stereotactic radiotherapy in the abdominal or pelvic region. Technol Cancer Res Treat. 2012 Dec;11(6):591-7. doi: 10.7785/tcrt.2012.500261. Epub 2012 May 7. PMID: 22568625; PMCID: PMC4527454.

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Digital Poster MRI-GUIDED RADIOTHERAPY IN PROSTATE BED IN PATIENTS WITH BIOCHEMICAL RELAPSE

Abrahams Ocanto 1 , Macarena Teja 1 , Daniela Gonsalves 1 , Fernando López 1 , Miguel Montijano 1 , Maia Dzhugasvilli 1 , José González 2 , Castalia Fernández 1 , Jon Andreescu 3 , Álvaro Flores 1 , Maria Gonzalez 1 , Isabel Garrido 1 , Lisselott Torres 1 , Beatriz Sevilla 1 , Diego Alcaraz 4 , Esther Holgado 4 , Giorgio Purrello 5 , Luis Glaría 1 , Felipe Couñago 1 1 Radiation Oncology, GenesisCare, Madrid, Spain. 2 Radiation Oncology, GenesisCare, Sevilla, Spain. 3 Radiation Oncology, GenesisCare, Córdova, Spain. 4 Medical Oncology, GenesisCare, Madrid, Spain. 5 Radiation Oncology, Hospital Ospedale San Gerardo, Monza, Italy Purpose/Objective: Stereotactic Body Radiotherapy (SBRT) to the prostate has emerged as a viable radical treatment option. However, limited evidence supports its use in the postoperative setting, where the standard of care remains hypofractionated radiotherapy achieving an EQD2 of approximately 70 Gy. This study reports on the tolerability of SBRT in patients with biochemical relapse criteria, utilizing adaptive radiotherapy. Material/Methods: Patients with prostate-specific antigen (PSA) levels >0.2 ng/mL following radical prostatectomy were enrolled in a prospective trial (Protocol No. 5289). Adaptive SBRT was delivered to the prostate bed using a 0.35T MR-LINAC system, administered in five fractions every other day to a total dose of 32.5 Gy (EQD2α/β=1.5 = 74.3 Gy). For patients with macroscopic recurrence, the dose was escalated to 35 Gy (EQD2α/β=1.5 = 85 Gy). Patient demographics, including median PSA levels, were documented. Acute and late toxicities were evaluated using the Common Terminology Criteria for Adverse Events (CTCAE v5.0).