BM-29 * NUMBER OF BRAIN METASTASES INFLUENCES SURVIVAL FOLLOWING GAMMA KNIFE RADIOSURGERY

Abstract

We sought to investigate the oncologic outcome of brain metastases (BM) patients treated with Gamma Knife Radiosurgery (GKRS) based on the number of metastases. The Columbia University Medical Center database was queried for patients treated with GKRS from 1998 to 2013. There were 526 patients (233 men) with median age 62 years. Patients were divided into two groups; group 1 included patients with 1-3 BM and group 2 included patients with 4-12 BM. Primary cancers included 257 (48.7%) lung, 102 (19.3%) breast, 62 (11.7%) melanoma, 40 (7.6%) renal cell, 29 (5.5%) gastrointestinal, and 36 (7.2%) other. 206 (39.2%) patients received GKRS alone, 109 (20.7%) GKRS plus whole brain radiotherapy (WBRT), 109 (20.7%) GKRS plus neurosurgical resection (NSG), and 102 (19.4%) all three modalities. 423 (80.4%) patients had 1-3 BMs and 103 (19.6%) had 4-12 BMs. Median overall survival (mOS) determined by Kaplan-Meier was 16.62 months. mOS for patients with 1-3 BMs and 4-12 BMs was 18.4 months and 13.0 months, respectively (log-rank p = 0.021). mOS for patients with 1-3 BM treated with GKRS alone, GKRS plus WBRT, GKRS plus NSG and all three modalities was 9.5, 20.6, 27.8, and 25.4 months respectively (p < 0.001), mOS for patients with 4-12 BM treated with GKRS alone, GKRS plus WBRT, GKRS plus NSG and all three modalities was 7.4, 15.2, 6.3, 16.4 respectively (p < 0.001). Age at time of treatment, KPS, primary disease status and treatment modalities were significant predictors of survival on univariate and multivariate analysis (p < 0.05). Gender, RPA class, GPA score were statistically significant only on univariate analysis (p < 0.05). Results indicate a significant difference in the overall survival between the two groups, also NGS was more effective in patients with 3 or less lesions, whereas WBRT was more effective in patients with greater number of lesions.