A Prospective, Multicenter, Observational Cohort Study to Evaluate the Efficacy and Safety of a Novel Anti-tumor Drug as a Radiosensitizer in Patients With Advanced Breast Cancer Brain Metastasis.

Inclusion criteria

• Males or females who are at least 18 years of age on the day of signing the informed consent form.
• Patients with advanced breast cancer that is inoperable and has metastasized to the brain, confirmed by histology or cytology.
• Patients who are planned to receive, currently receiving, or have completed intracranial radiotherapy after discussion by a multidisciplinary team (MDT) at the stage of brain metastasis.
• Patients who are planned or currently receiving a systemic treatment regimen with a novel anti-tumor drug selected by the physician, within 3 weeks before radiotherapy, during radiotherapy, or within 3 weeks after completion of radiotherapy. These drugs include:

ADC drugs (such as T-DXd, T-DM1, etc.), CDK4/6 inhibitors, TKI drugs (such as Pyrotinib, Tucatinib, etc.), Novel chemotherapy drugs (such as Utidelone, Irinotecan liposomes, etc.), Bevacizumab, PD-1/PD-L1 inhibitors, etc.

• Patients with a traceable medical history during the treatment period.
• Patients who are able to sign the informed consent form to participate in the study.

Exclusion criteria

• The subject has leptomeningeal metastasis.
• If the patient has concurrent brain metastasis, the neurological symptoms are too severe to cooperate with radiotherapy.
• The subject has not signed the informed consent form.
• Pregnant or breastfeeding women.
• Other situations deemed by the investigator as unsuitable for inclusion in the study.