Abstract: Brain metastasis (BM) is considered one of the major causes of mortality in breast cancer patients. BM develops more frequently in triplenegative breast cancer and human epidermal growth factor receptor 2 (HER2)positive breast cancers, while the incidence of BM in hormone receptor positive is much lower. Mutations and expression of BM of breast cancer are differ from their primary tumors. Importantly, some therapeutic actionable mutations can be present in the BM while not in the primary tumors. Current targeted therapeutics in BM of breast cancers are limited, and drugs used have proven effects on the primary tumors but lack specificity for the BM. The identification of genomic and expressional alterations specific to BM are crucial to the development of BM specific targeted therapies.

Key words: Breast neoplasms, Brain metastasis, Mutation, Targeted therapy