Hormone therapy (tamoxifen, aromatase inhibitors).  Targeted therapy (e.g., trastuzumab, lapatinib, pertuzumab, mammalian target of rapamycin {mTOR} inhibitors, and cyclin-dependent kinases (CDK4/6 inhibitors).  Chemotherapy.  Surgery, for patients with limited symptomatic metastases.  Radiation therapy, for patients with limited symptomatic metastases.  Bone modifier therapy, for patients with bone metastases.  Cytologic or histologic documentation of metastatic disease is obtained whenever possible.  Treatment of metastatic breast cancer will usually involve hormone therapy and/or chemotherapy with or without trastuzumab.  All patients with metastatic breast cancer are considered candidates for ongoing clinical trials.

Source:  NCI 2019