RDTA-15 SAFETY AND EFFICACY OF STEREOTACTIC RADIOSURGERY FOR 15 OR MORE BRAIN METASTASES

Abstract PURPOSE Stereotactic radiosurgery (SRS) is a mainstay treatment for patients with limited brain metastases (BM). As advancements in systemic therapies have prolonged survival in metastatic disease, evaluating the role of SRS in patients with high intracranial disease burden is increasingly important. METHODS In this IRB-approved, single-institution retrospective study, we analyzed patients with at least 15 SRS-treated BMs between 2010-2023. Patient demographics, disease characteristics, treatment details, and toxicities were summarized descriptively. Kaplan-Meier analysis was used to estimate overall survival (OS), freedom from whole-brain radiation therapy (FFW), and freedom from neurological death (FFN). RESULTS Ninety patients were included with a median number of 18 BMs treated (range, 15-32) and 2 SRS courses per patient (range, 1-8). Lung cancer was the most common primary malignancy (47.3%). Most patients had good baseline function (84.9% ECOG 0–1 or KPS >70), and 67% were neurologically asymptomatic at SRS initiation. Median follow up was 15 months (range, 0-118). Radiation necrosis occurred in 10% of patients and 17.2% were hospitalized for neurologic symptoms within 30 days of SRS. Leptomeningeal disease developed in 13.2% of patients with a median time to development of 12.7 months. The mean cumulative whole brain dose across SRS courses was 5.28 Gy. Median and 1-year OS was 27.8 months and 63.2%, respectively. One-year FFN and FFW were 87.3% and 70.8%, respectively. Median time to intracranial progression and salvage therapy following initial SRS was 4.1 and 5.3 months. CONCLUSION SRS can be safely and effectively used in patients with extensive BMs, delaying the need for WBRT while preserving neurologic function and quality of life. Cumulative brain dose remained low and below hippocampal constraints typically used in hippocampal avoidance WBRT.