HER2-positive Breast Cancer Brain Metastases: Multiple Responses to Systemic Chemotherapy and Trastuzumab—a Case Report

Brain metastases from metastatic breast cancer typically occur in 10–15% of patients and are associated with survival of 3–6 months. Recent series have shown that women with HER2-postive metastatic breast cancer receiving the drug trastuzumab develop brain metastases more frequently than this, but also that continuation of trastuzumab after diagnosis of brain metastases in such patients is associated with extended survival. Authors have speculated that this is due to improved systemic control of disease; however, a possibility is that trastuzumab may have a beneficial effect on cerebral metastases themselves. We report the case of a woman with HER2-positive metastatic breast cancer who developed multiple brain metastases while on trastuzumab, in whom the addition of systemic chemotherapy to continued trastuzumab has produced multiple treatment responses associated with prolonged survival. This is the first report of its kind.