Breast cancer is the second most common cancer associated with brain metastases in the United States . As patients with advanced breast cancer live longer, the incidence of brain metastases appears to be increasing. In a subset of women, progression in the central nervous system (CNS) has become the major life-limiting problem.
The risk factors, prognosis, and management of brain metastases in breast cancer are presented here. An overview of the presentation, diagnosis, and management of brain metastases (across tumor types) is discussed separately.
The risk of central nervous system (CNS) relapse among patients with breast cancer varies significantly by disease stage. Among women presenting with early stage breast cancer, less than 3 percent will go on to develop brain metastases [1,2]. In contrast, symptomatic brain metastases are diagnosed in 10 to 16 percent of patients with metastatic breast cancer [1,3]. Factors associated with an increased likelihood of CNS relapse include age under 40 years, pulmonary metastases, and African American ancestry [1,3-7].
In addition, the breast cancer subtype appears to be associated with the incidence of brain metastases [2,6,8-19]. In a cohort study of 1434 women treated with breast conserving therapy plus systemic chemotherapy, brain metastases developed in 36 (2.5 percent) . However, the risk of brain metastases at ten years differed by breast cancer subtype: