A Study of Surgery and Radiotherapy in People With Breast Cancer

The researchers are doing this study to see if the combination of surgery, locoregional radiation therapy, SBRT (stereotactic body radiation therapy), and the usual approach is more effective in treating oligometastatic HER2-positive breast cancer than the usual approach alone. The researchers will also study the side effects of the study treatment.

Prior to randomization, patients will receive standard of care first-line systemic therapy as defined by NCCN guidelines (paclitaxel, trastuzumab and pertuzumab at the time of study activation). Following a 3-12 month period without evidence of progression as determined by the treating clinician, patients may be registered and then randomly assigned in 1:1 fashion to one of two study arms. All patients will be followed until progression of disease or 3 years after randomization, whichever comes first. All HER2-directed agents are FDA-approved and administered per standard of care practice.