A Real-World Study of Inavolisib in Patients With HR-Positive/HER2-Negative, PIK3CA-Mutated Advanced Breast Cancer

Inclusion Criteria: * Histologically or cytologically confirmed HR+/HER2- recurrent or metastatic breast cancer. * Presence of a pathogenic PIK3CA mutation confirmed by tissue or plasma-based NGS/PCR testing. * Availability of traceable electronic medical records, imaging, laboratory, and follow-up data at baseline. * Initiated treatment with "Inavolisib + Endocrine Therapy" with or without a CDK4/6 inhibitor in real-world clinical practice, with complete and traceable regimen information. * Provision of informed consent for this non-interventional study (if required by the center's ethics committee). Exclusion Criteria: * Concurrent participation in any interventional clinical trial at enrollment. * Presence of another active malignancy requiring concurrent systemic therapy, or missing core data preventing outcome assessment. * Any condition (psychiatric, social, geographical) that would preclude adequate follow-up, as judged by the investigator.