ESTRO 2025 - Abstract Book

S746

Clinical - CNS

ESTRO 2025

References: 1. Marwah, R., et al. Reirradiation versus systemic therapy versus combination therapy for recurrent high-grade glioma: a systematic review and meta-analysis of survival and toxicity. J Neurooncol 164, 505–524 (2023). https://doi.org/10.1007/s11060-023-04441-0 2. van Linde, M.E., et al., 2017. Treatment outcome of patients with recurrent glioblastoma multiforme: a retrospective multicenter analysis. J. Neurooncol. 135 (1), 183–192. https://doi.org/10.1007/s11060-017-2564-z.

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Digital Poster Consecutive radiosurgery for multiple brain metastases with CyberKnife Robotic Radiosurgery Unit: Outcomes and Predictive Factors at a Hospital Center Ignacio María Gómez Paloma 1 , Mercedes Martín Sánchez 1 , David Sevillano Martínez 2 , Eva Fernández Lizarbe 1 , Margarita Martín Martín 1 , Carolina De La Pinta Alonso 1 , Juan David García Fuentes 2 , Julen Azcona Martín 1 , Marta Camacho Manzanares 1 , Adrián Durango Méndez 1 , María Dolores Espinosa Cuesta 1 , Isabel Alvira Ortiz 1 , Sonsoles Sancho García 1 1 Radiotherapy Oncology, Universitary Hospital Ramon y Cajal, MADRID, Spain. 2 Radiotherapy physics, Universitary Hospital Ramon y Cajal, MADRID, Spain Purpose/Objective: Recently, whole-brain radiotherapy has been replaced by Stereotactic Radiosurgery (SRS), with equal results in overall survival and improvement in patients' quality of life. This strategy requires close monitoring of the appearance of new brain metastases for early treatment. We analysed the results obtained in terms of overall survival, brain progression-free survival and toxicity in patients who have required at least two consecutives SRS treatments due to the appearance of new brain metastases. Material/Methods: We retrospectively analysed patients treated between January, 2020 and August, 2024, in our center with two or more courses of SRS due to the development of new brain metastases. All of them were treated using Cyberknife. Patient and treatment characteristics, and dosimetric data were collected. Overall and brain progression-free survival were analysed by the Kaplan-Meier method. Results: 42 patients met criteria to be analysed. Total number of lesions treated was 434 for the whole group. Median number of lesions treated were 10,3 (ranged 2-53). The mean age of the patients was 63 years. Twenty-six (61.9%) patients were male, with a Karnofsky index of 90 or higher in 81% of the cases. The most frequent primary tumor was non-small cell lung cancer in 26 patients (61.9%), followed by melanoma 7 (16.7%) and breast cancer 5 (11.9%). The most commonly used dose schedule was 21Gy in a single fraction. Two consecutive SRS were performed in 27 patients (64.3%), 3 treatments in 9 (21%), 4 treatments in 4 (9.5%) and 5 treatments in 2 (4.8%). The median follow-up was 17 months. The median OS was 30 months (50.4% at 2 years). The median second brain recurrence free survival was 21 months (33.7% at 2 years). Acute toxicity < grade II occurred in 5 patients (11.9%). We can report 9 cases (21%) of radiologic radiation necrosis (RN), none of them symptomatic, and was higher in patients treated 3 or more times compared to those treated twice (18.5% vs 26.7%), although these differences were not statistically significant. We have found no statistically significant differences in radionecrosis incidence and the total number of lesions treated (RN 9,8 vs no RN 10,6 metastases) or the total volume of the lesions (RN 19.6 vs no RN 14.2 cc). Conclusion: Performing consecutive courses of ablative, SRS for multiple brain metastases, including patient with large number of lesions or multiples courses of treatment, achieves acceptable rates of brain progression-free survival with