Prognostic role of triple-negative subtype in breast cancer patients with brain metastases.

Abstract

36 Background: Metastatic breast cancer (MBC) patients with brain metastases (BM) have a poorer prognosis compared to patients with metastases to sites such as bone or other visceral organs. The role of breast cancer subtypes such as triple negative (TN) status and its relationship with other known prognostic factors have not been well delineated in the context of metastatic disease to the brain. We conducted a retrospective single institution cohort study of MBC patients with BM to evaluate the association between TN subtype and overall survival from the diagnosis of BM. Methods: Baseline demographic and tumor specific data including ER, PR and HER2 status were collected on newly diagnosed MBC patients between January 1998 and December 2009. Overall survival was determined from the date of diagnosis of BM. Survival analyses were performed using the Kaplan-Meier method and Cox proportional-hazards model. Results: Data were available on 186 MBC patients with BM, of whom 156 died during a median follow-up of 10.2 months from the diagnosis of BM; median age was 47.9 years. 91% of patients were Caucasian; 25.3% had triple negative disease. Median survival from the period of diagnosis of BM in patients with triple negative disease was 7 months (Interquartile range, IQR: 3–13) as compared to 11 months (IQR: 5–22) in patients who were HER2-positive or ER/PR-positive. Multivariate analysis found a higher risk of death after BM for TN disease subtype, with a hazard ratio for death of 2.89 (95% confidence interval: 1.89–4.44; p<0.001), when adjusted for variables such as age and stage at initial diagnosis of breast cancer, race, the number of metastatic sites, and the use of metastatic chemotherapy. The administration of metastatic chemotherapy had a significant survival benefit in the analyses, with a hazard ratio for death of 0.52 (95% CI: 0.27–0.99; p=0.048). Conclusions: This retrospective cohort study in MBC patients with BM provides evidence for a greater risk of death in those with TN disease as compared to HER2-positive or ER/PR-positive subtypes even after adjusting for other prognostic factors.