Retrospective study of survival among patients with HER2-positive metastatic breast cancer and central nervous system disease

Approximately one-third of patients with HER2-positive metastatic breast cancer (mBC) develop brain metastasis. It is unclear whether patients with disease limited to the central nervous system (CNS) have different outcomes and causes of death compared with those with concomitant extracranial metastasis. A retrospective cohort study at Memorial Sloan Kettering Cancer Center (New York, NY) assessed overall survival and CNS-related mortality among patients with HER2-positive mBC and a diagnosis of CNS disease by disease distribution (CNS only versus CNS plus extracranial metastasis. In this cohort study of 274 patients with HER2-positive mBC and CNS metastasis, 55.2% of deaths were due to CNS-related causes, with the greatest risk among patients with leptomeningeal disease. Patient with CNS-only disease had longer overall survival and lower risk of death from any cause compared with patients with concomitant extracranial metastases, but CNS-only presentation was associated with higher risk of CNS-related death. The authors conclude that these findings suggest that aggressive treatments (both local and systemic) may be warranted to control the intracranial progression of CNS metastases.