Prognostic factors for brain metastatic tumors treated with stereotactic radiosurgery

Objective To assess the clinical outcome of brain metastatic tumors treated with linac-based stereotactic radiosurgery (SRS) and evaluate the potential prognostic factors. Methods We reviewed 102 patients with 131 brain metastatic tumors treated with a linac-based SRS from 1994 to 2002, including 78 patients with solitary and 24 with multiple brain metastases, with the diameter of tumor all within 4 cm. Among these 102 patients, 18 received planned whole-brain radiation therapy (WBRT) before or after SRS. Ninety-three patients with 120 lesions were evaluated for local tumor control analysis with follow-up imaging data. The patients' survival and local control of the tumors were estimated using Kaplan-Meier method, and the potential prognostic factors were analyzed with univariate and multivariate analysis. Results The overall local tumor control rate and the actuarial local tumor control rate at 1 year were 92.5% and 87.6%, respectively. The tumor volume was the single significant predictor for local tumor control (P=0.035). The median survival of the 102 patients was 11 months. In univariate analysis, patients aged over 60 years (P=0.038) with KPS score above 70 (P=0.001), absence of extracranial metastases (P=0.031) and administration of planned WBRT (P=0.025) were significant factors for survival. After adjustment of multivariate analysis, only KPS score was identified as the independent predictor (P=0.033). Conclusion SRS is an effective method for treatment of brain metastases, and multiple factors may affect the local tumor control and survival of the patients.