The strategy of repeat stereotactic radiosurgery without whole brain radiation treatment for new brain metastases: Outcomes and implications for follow-up monitoring

Purpose: Stereotactic radiosurgery (SRS) is widely used to treat brain metastases in place of whole brain radiation therapy (WBRT), with the goal of reducing treatment toxicity balanced against the risk of developing new metastases. We evaluated outcomes of repeated courses of SRS in the management of new brain metastases as an alternative to salvage WBRT. Methods and materials: We conducted a single-institution retrospective review of 239 patients treated with SRS without WBRT for brain metastases from 2004 to 2014. Eighty-six patients received at least 2 courses of SRS for new brain metastases. Outcome metrics included survival, development of symptomatic new brain metastases, neurologic symptoms at death or last follow-up, and ultimate WBRT. Results: Eighty-six patients (median age, 59 years) underwent a median of 2 courses of SRS (range, 2-6), with a median of 2 lesions treated initially and on retreatment. The median interval between SRS treatments was 5.8 months (range, 1.2-69.1). New brain metastases after initial radiosurgery were detected by routine imaging in 87% of cases. Median overall survival from repeat SRS was 13.0 months (range, 0.3-64.5) and from initial brain metastasis diagnosis 25.0 months (range, 2.0-68.1). On multivariate analysis, Eastern Cooperative Oncology Group performance status 0-1 (hazard ratio [HR], 0.37; 95% confidence interval [CI], 0.15-0.90; P=.029), controlled extracranial disease (HR, 0.35; 95% CI, 0.13-0.94; P=.038), and interval between initial and second SRS >6 months (HR, 0.49; 95% CI, 0.25-0.96; P=.037) correlated with improved overall survival from brain metastasis diagnosis. A total of 24.7% of patients had symptomatic intracranial metastatic disease at death or last follow-up, and 26.7% ultimately received WBRT. Conclusion: Repeated SRS is a reasonable option for patients with new brain metastases, as our results suggest favorable survival outcomes with this approach. New lesions infrequently caused neurologic symptoms before routine imaging detection, and a minority of patients had symptomatic intracranial disease at death or last follow-up. (C) 2016 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.