COntinue the SaMe Systemic Therapy After Local Ablative Therapy for Oligo Progression in Metastatic Breast Cancer - the COSMO Study

This study (COSMO) looks at whether patients with metastatic breast cancer whose disease has started growing in just one or two spots can continue their current systemic treatment after treating those spots locally (e.g., with radiation or ablation). This is called "oligoprogression." **You may be eligible if...** - You have metastatic breast cancer confirmed by biopsy - Only one or two specific spots have started growing (oligoprogression), while the rest of the disease is stable - You have been on your current systemic therapy (hormone therapy, chemotherapy, targeted therapy, or immunotherapy) for at least 6 months - The growing spots can be treated with local therapy (radiation, surgery, or ablation) **You may NOT be eligible if...** - More than two lesions are growing, or spread is to multiple organs - You have not been stable on treatment for at least 6 months Talk to your doctor to see if this trial is right for you.