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.

"1. Novel anti-tumor drugs \[including: ADC drugs (such as T-DXd, T-DM1, etc.), CDK4/6 inhibitors, TKI drugs (such as Pyrotinib, Tucatinib, etc.), novel chemotherapy drugs (such as Utidelone, Irinotecan liposomes, etc.), Bevacizumab, PD-1/PD-L1 inhibitors, etc.\]~2. Radiotherapy"