Patients with Long-Term Control of Systemic Disease Are a Favorable Prognostic Group for Treatment of Brain Metastases with Stereotactic Radiosurgery Alone

BACKGROUND: Stereotactic radiosurgery (SRS) alone is an attractive option for treatment of brain metastases. SRS avoids whole-brain radiotherapy (WBRT)-associated morbidity, but is limited by regional central nervous system (CNS) failures and short survival in some patients. We evaluated a subgroup of patients with controlled systemic disease that could represent a favorable patient population for SRS alone. METHODS: All patients with brain metastases treated with SRS without WBRT at our institution between 2004 and 2014 were grouped into two cohorts: those with controlled systemic disease (CSD) for 1 year or longer before prior to presentation with brain metastases and those without (i.e., uncontrolled systemic disease [USD]). Rates of local and regional CNS failure, and overall survival were assessed with x(2) and Student t tests. Cox regression analysis was performed to evaluate independent predictors of regional control and overall survival. RESULTS: Two hundred ninety-four patients underwent SRS to 697 lesions, of which 65 patients had CSD. Median follow-up was 9.7 months. There was no difference in local control between the two cohorts (P = 0.795). Regional CNS control was significantly better for patients with CSD (68% vs. 48%; P = 0.001). Overall survival at 1 and 5 years for CSD were 65% and 13% with USD yielding 41% and 7%, respectively (P < 0.001). Multivariate analysis demonstrated that USD (relative CSD) independently predicts regional failure (hazard ratio [HR], 1.75; P = 0.008) and shorter overall survival (HR, 1.55; P = 0.007). CONCLUSIONS: Patients with brain metastases after 1 year or longer of primary and systemic disease control represent a particularly favorable cohort, with lower regional CNS failure and prolonged survival, for an approach of SRS alone.