A Study on Adding Precisely Targeted Radiation Therapy (Stereotactic Body Radiation Therapy) to the Usual Treatment Approach (Drug Therapy) in People With Breast Cancer

Inclusion Criteria

• •Age 18 or older
• •Willing and able to provide informed consent
• •Metastatic breast cancer, biopsy proven
• •* ER+/HER2-, defined as \>5% ER+ staining
• •* HER2+ (regardless of ER status), including HER2-low and high expressors
• •History of at least 6 months, sustained response to systemic therapy (clinically or radiographically defined as complete or stable response without progression)
• •Isolated site of disease progression on FDG PET scan
• •Consented to 12-245
• •ECOG performance status 0-1