BMET-12SURVIVAL IN BREAST CANCER PATIENTS WITH BRAIN METASTASES AFTER GAMMA KNIFE STEREOTACTIC RADIOSURGERY

Abstract

BACKGROUND: Recent studies have suggested a difference in outcome for breast cancer patients with brain metastases based on breast cancer subtype. These subtypes are defined as ER/PR+ and HER2- (luminal A), ER/PR+ and HER2+ (luminal B), ER/PR- and HER2- (triple-negative), and ER/PR- and HER2+ (HER2). The recently published modified Graded Prognostic Analysis (GPA) score for predicting overall survival (OS) in these patients includes subtype, number of CNS metastases, age, and performance status. We investigated whether this model was predictive of outcomes in these patients treated with Gamma Knife Stereotactic Radiosurgery (GKRS) at our institution and if any additional factors were predictive. METHODS: We reviewed all patients treated by GKRS for brain metastases from breast cancer at our institution from 2000 to 2014. Characteristics included subtype, age at breast cancer diagnosis, clinical stage, chemotherapy, age at diagnosis of brain metastases, Karnofsky Performance Status, years between breast cancer diagnosis and brain metastases, number of brain metastases, extracranial metastases, controlled primary tumor, type of treatment, and GPA score. OS was calculated using the Kaplan-Meier method and Cox regression analysis was performed to identify predictors. RESULTS: 61 patients were included. The majority of patients had luminal type. These patients were more likely to present with multiple metastases (p = 0.024). The median survival after treatment for the entire cohort was 16 months. We found no significant difference in survival based on subtype. According to GPA score, patients with the highest score had the best OS (p = 0.112). Multivariate analysis showed that stage II or III breast cancer at diagnosis, more than three brain metastases, and treatment with surgery and whole brain radiation for brain metastases were predictors for worse OS. CONCLUSION: In our cohort, breast cancer subtype is not a significant predictor for survival in these patients. The breast-cancer specific GPA was a good predictor of OS.