"It is estimated that 10-35% of patients diagnosed with breast cancer will develop metastasis to the brain. Although patients with localized disease have a low probability of initial brain metastasis (BM), those with regional and metastatic disease have a 7.6% and 13.5% risk of BM at diagnosis, respectively, while those with HER-2 positive disease or ER-negative disease may be at an even higher risk, especially in the context of other visceral metastases, such as the liver. Current international guidelines for the evaluation of a new patient with breast cancer recommend screening for BM only if there are suspicious clinical symptoms, and not as a routine test. For patients with neurological symptoms, such as progressive headache, motor dysfunction, or sensation changes, there should be a low threshold for ordering an MRI of the brain. Treatment options for breast cancer brain metastases (BCBM) include surgery with/without adjuvant radiotherapy (whole brain or tumor-bed alone), whole-brain radiotherapy (with or without a focal boost, such as radiosurgery), radiosurgery alone, and potentially, systemic or targeted therapy, either used singly or in conjunction with other localized therapeutic approaches."
Management of solitary and multiple brain metastases from breast cancer (2015)
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4477383/