Outcomes and Prognostic Factors for Patients With Brainstem Metastases Undergoing Stereotactic Radiosurgery

Abstract

Treatment of tumors metastatic to the brainstem with stereotactic radiosurgery (SRS) has not been widely studied. To identify the effects of SRS on patients with brainstem metastases by assessing duration of local progression-free survival (LPFS) and overall survival. We retrospectively reviewed clinical data collected from 60 patients undergoing linear accelerator-based SRS for tumors metastatic to the brainstem between August 1994 and December 2007. The LPFS and overall survival were calculated with the Kaplan-Meier method. Prognostic factors were evaluated with the log-rank test and Cox proportional hazards model. The median age of patients was 61 years (range, 39-85 years); the median treated lesion volume was 1.0 mL (range, 0.1-8.7 mL); and the median SRS dose was 15 Gy (range, 8-18 Gy). The median overall survival interval after SRS was 4 months (95% confidence interval, 3.4-4.9 months); crude local tumor control was 76%; and median LPFS was 5.7 months (95% confidence interval, 3.0-8.4 months). Shorter overall survival was associated with a pretreatment tumor volume ≥4 mL (P < .001) and male sex (P = .03). Shorter LPFS was associated with a pretreatment tumor volume ≥4 mL (P = .008), a melanoma primary tumor (P = .002), and the presence of necrosis in pre-SRS magnetic resonance imaging (P = .04). A Basic Score for Brain Metastases of 2 to 3 vs 1 (P = .007) and a Score Index for Radiosurgery >5 (P = .003) were significantly associated with longer survival. Twelve patients (20%) developed SRS-related complications. Stereotactic radiosurgery provides noninvasive treatment and favorable local tumor control for patients with brainstem metastases.