Purpose: The implications of margin expansions on local control (LC) and radionecrosis (RN) for treating brain metastases (BMs) with stereotactic radiosurgery (SRS) remain unclear. We performed a systematic review and meta-analysis to compare LC and RN between patients with BMs treated with SRS planned with no margin versus a margin.
Methods and materials: We used the Population, Intervention, Control, Outcomes, Study Design; the Preferred Reporting Items for Systematic Reviews; and Meta-analyses, and the Meta-analysis of Observational Studies in Epidemiology selection inclusion criteria for studies of patients with BMs treated with SRS with no margin or a margin. Primary outcomes were 1-year LC and radiographic and symptomatic RN incidences. Weighted random effects meta-analyses were performed to compare effect sizes.
Results: Across 17 studies, we identified 5015 lesions treated with SRS (1360 lesions with no margin and 3684 with a margin). The median total margin was 1.5 (range, 1-3) mm. Single-fraction SRS was most common with a median prescription dose of 21 Gy (range, 15-24 Gy). The estimated 1-year LC rate was similar with a margin (88.4% [95% CI, 83.7%-92.4%]) versus without (83.0% [95% CI, 69.3-93.2%; P = 0.28]). The estimated incidences of radiographic RN after SRS with or without a margin were 9.2% (95% CI, 0.2%-29.6%) and 7.0% (95% CI, 4.1%-10.7%; P = 0.56), respectively. The estimated incidences of symptomatic RN after SRS without or with a margin were 8.6% (95% CI, 5.2%-12.7%) and 4.1% (95% CI, 0.9%-9.3%), respectively (P = .24).
Conclusions: We did not note a significant difference in LC or RN between patients treated with or without margin expansions. Prospective evaluations are warranted to further assess this question while controlling for other relevant treatment planning and metastasis considerations.
Copyright © 2025 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.