ESTRO 2025 - Abstract Book

S750

Clinical - CNS

ESTRO 2025

4291

Digital Poster 10 years of SRS Single isocenter to multiple brain metastases Results Paola Zuccoli, Francesca Giannetti, Alessandro Molinari, Claudia Menichelli, Gabriella Pastore, Christian Fierro, Alessandro Fanelli Radiotherapy, Ecomedica - Ergea Group, Empoli, Italy Purpose/Objective: Stereotactic Radiosurgery (SRS) is an excellent option in cases of brain metastases (BMs). SRS is a non-surgical procedure that delivers precisely-targeted high dose of radiation in only a single treatment by means of highly focused beams, relying on several advanced technologies to guarantee high degree of dose conformity and accuracy of beam delivery while minimizing dose to the surrounding normal tissue. Given that SRS can treat more than one tumor per session, this mono-institutional retrospective analysis evaluated the brain monoisocentric SRS results in terms of overall survival (OS) and local control (LC) for patients treated using radiobiologically based image guided Volumetric Modulated Radiosurgery. Material/Methods: From January 2013 to October 2024, 104 pts were enrolled (48M and 56F), and 742 BM were treated with curative intent. The median age at the diagnosis was 58.7 years (28-85). The median dose was 18Gy at isodose of 70% in single fraction. Primary tumor histology was: lung (60.57%), breast (16.34%), and colon-rectal (5.8%). Primary tumor was controlled in all patients. SRS was delivered by 6MV LINAC with multiple non coplanar arcs. Before each fraction, isocenter position was verified by CBCT. Mean single lesion CTV volume was 0.796cc (range 0.016-6.904cc) and mean total volume of single treatment was 3.660cc (range 0.578-13.881cc). The median number of BM was 4 (range 3 15). Inclusion criteria were: patient with multiple BM’s, WHO/ECOG performance status 0-2. Results were evaluated by multiphasic CT or RM scan. Moreover for some patients and always in suspect recurrences, 11C-methionine PET or RM spectroscopy was performed. Results: We analyzed the SRS results in terms of OS and LC. Median follow up was 10.5 months (range 0.1-74.8 months), 5.8% of pts was still alive. OS is 69.2%, 44.2%, 38.5% and 27.9% at 3,6,9 and 12 month respectively. LC was 61.5%, 29.8%, 23.1% and 22.1% at 3,6,9 and 12 month respectively. Mean healthy brain dose was 2.2Gy. 3.9% of pts presented radio necrosis. Only one pts (<1%) presented recurrent disease after 14months and was retreated by SRT. Conclusion: Long-term outcomes in a large cohort of patients treated with radiobiologically based image guided Volumetric Modulated Radiosurgery have confirmed its safety and efficacy. The reduced treatment time and the ability to preserve healthy brain tissue make it feasible to manage patients with numerous metastases and to administer multiple SRS sessions. In specific cases, WBRT can be deferred

Keywords: Brain metastasis, SRS, monoisocentric