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

Inclusion Criteria:

Subjects are eligible for inclusion in the study only if all the following criteria apply:

1. Men or women who are 18 years of age or older on the day of signing the informedconsent;

2. Patients with advanced breast cancer that is inoperable or has metastasized,confirmed by histology or cytology;

3. Patients who, after MDT discussion at the metastatic breast cancer stage, areconsidered suitable for radiotherapy and have completed radiotherapy;

4. Patients who have previously received and continue to use immunotherapy, or areplanned to receive immunotherapy, and are scheduled to receive a systemic treatmentregimen including immunotherapy as chosen by the physician within 3 weeks aftercompleting radiotherapy;

5. Patients with a traceable medical history during treatment;

6. Subjects who are able to sign an informed consent to participate in the study.

Exclusion Criteria:

1. Subjects with brain metastases or leptomeningeal metastases; if there are anysuspected symptoms or signs of CNS involvement, they should be excluded by a cranialMRI scan;

2. Have not signed the informed consent form;

3. Pregnant or lactating women;

4. Other conditions deemed unsuitable for inclusion in the study by the investigator.