A Prospective, Multicenter, Observational Cohort Study Assessing the Efficacy and Safety of Radiotherapy-sensitized Immunotherapy in Advanced Breast Cancer

This observational study is tracking real-world outcomes for people with advanced (inoperable or metastatic) breast cancer who have received radiation therapy followed by immunotherapy. The goal is to understand whether radiation enhances the effectiveness of immunotherapy — a concept known as the 'abscopal effect.' **You may be eligible if...** - You are 18 years or older - You have advanced breast cancer confirmed by biopsy that has spread or cannot be operated on - You have completed radiotherapy as decided by a multidisciplinary team - You are receiving or are planned to receive immunotherapy within 3 weeks of completing radiation - Your medical history is available for review **You may NOT be eligible if...** - You have not had radiation therapy for your advanced breast cancer - You are not receiving immunotherapy as part of your treatment plan - Your medical history cannot be traced Talk to your doctor to see if this trial is right for you.