Pembrolizumab And Stereotactic Radiosurgery (Srs) Of Selected Brain Metastases In Breast Cancer Patients

This trial is testing whether the immunotherapy drug pembrolizumab (Keytruda) combined with focused radiation to a few brain metastases (stereotactic radiosurgery) can improve outcomes for breast cancer patients whose cancer has spread to the brain. **You may be eligible if...** - You are 18 years or older - You are in generally good health (ECOG status 0–1) with adequate neurological function - You have metastatic breast cancer with at least 2 and no more than 10 brain tumors (each at least 5mm in size) that have not been previously treated - The brain tumors are visible on a contrast MRI scan done within 2 weeks before treatment - Each tumor to be treated is smaller than 4 cm **You may NOT be eligible if...** - You have more than 10 brain metastases - Your tumor is too large (4 cm or more) - You have previously received immune checkpoint therapy - You have active autoimmune disease or are on systemic steroids - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.