Targeting the Sanctuary Site: Options when Breast Cancer Metastasizes to the Brain

Brain metastasis is a poor prognostic factor in breast cancer progression, and traditional treatment options have shown minimal response with overall low median survival rates. The incidence of brain metastasis has been increasing despite and, in part, due to advancements in treatment as a result of prolongation of survival. Targeted therapy such anti-HER2 agents have a lower efficacy in this setting compared to metastases elsewhere; however, novel therapies are emerging in this regard. In this comprehensive review, we discuss risk per subtype, special considerations for therapy selection, current focal and systemic treatments, and recent advancements and potential future targets for success. We present our treatment paradigm and multidisciplinary approach to brain metastases arising from breast cancer based on the available evidence, incorporating molecular characteristics.