Clinical Research Directory

Inclusion Criteria: * 18 years of age and above; * Women of any menstrual status; * Histologically confirmed recurrent or metastatic breast cancer, including patients initially diagnosed as stage IV or locally advanced inoperable; * Patients with histological pathology that is clearly HR-positive/HER2-negative breast cancer, or if there is metastatic pathology, the histological pathology of the metastatic foci shall prevail. (Those with ER intensity \>1% cellular nuclear staining) * Patients have at least 3 more fully documented medical records at the enrolled centre, including at least 1 inpatient record. Exclusion Criteria: * CDK4/6 inhibitors as neoadjuvant or adjuvant therapy; * Significantly missing diagnostic and treatment data from patients' medical records; * Participation in other clinical trials before and during the data collection period.