Single Arm Phase II Study of Fractionated Stereotatic Radiation Therapy (FSRT) for Bone Metastases in Breast Cancer

This study is evaluating a precise radiation technique called fractionated stereotactic radiation therapy (FSRT) — which delivers focused, high-dose radiation in multiple sessions — for treating bone metastases (cancer that has spread to the bones) in patients with breast cancer. **You may be eligible if...** - You have a confirmed diagnosis of invasive breast cancer - You have bone metastases confirmed by MRI within 4 weeks - Your tumor in the bone is at least 2mm away from the spinal cord (or has been surgically treated if closer) - You have no more than 3 separate spinal metastasis sites, and each involves no more than 2 adjacent vertebrae - You are in reasonably good health (KPS ≥40 or ECOG 0–2) - You have previously tried conventional radiation or surgery, or are unable to have surgery **You may NOT be eligible if...** - Your spine is structurally unstable or you have spinal cord compression that needs immediate treatment - You have a pacemaker or cannot lie flat for 30 minutes or cannot have an MRI - You have had prior radiation to the same spinal area within 3 months - You are pregnant - You have serious conditions like severe heart disease or end-stage kidney disease - You had chemotherapy within 2 weeks of starting treatment Talk to your doctor to see if this trial is right for you.