Brain metastases in breast cancer: Different survival by biological subtype and Ki67 expression

Abstract

1069 Background: Ten to 15% of patients (pts) with breast cancer will be diagnosed with central nervous system (CNS) metastases, and autopsy series suggest that up to 30% of pts have evidence of CNS disease at the time of death. The idenfication of factors that may predispose to CNS metastasis may help lead to earlier detection and possibly to improvement in disease management. Methods: Breast cancer pts with CNS metastases were identified within a database of 1300 breast cancer diganoses from 1995 to 2007 at the Department of Oncology, Azienda ULSS 13 VE. Pathologic features of tumor samples were examined using standard immunohistochemical assays. Results: Fifty-one pts with CNS metastases were identified. Median age at primary breast cancer diagnosis was 49 years (range, 28–78); median time to CNS metastases was 45 months (range, 3–244). HER2 overexpression was found in tumors from 25 pts (49.0%); 23 pts had tumors lacking overexpression of HER2, estrogen receptors (ER), and progesterone receptors (PgR) (ie, “triple negative” disease). Overexpression of p53 (at least 20% tumor cells positive), Ki67 (at least 20%), and BCL2 (at least 30%) were detected in tumors from 16 pts (31.4%), 32 pts (62.7%), and 14 pts (27.5%), respectively. Median survival from CNS involvement was 3.67 months (95% CI 2.05–5.28), with 24.4% and 15.3% of patients estimated to be alive at 12 and 24 months, respectively (Kaplan-Meier product limit method). A Cox proportional hazards analysis found that Ki67 overexpression was the only factor independently associated with a significantly increased risk of death (2.7-fold increase, p=0.028), while triple negative status was associated with a 1.8-fold increase in the risk of death (P=0.08) (Table). Conclusions: In our series of breast cancer pts with CNS metastases, nearly all had either HER2 overexpression or triple-negative disease. Pts whose tumors had higher proliferative indices, assessed by Ki67, had the poorest prognosis. [Table: see text] [Table: see text]