Talzenna will be approved for the treatment of gBRCA advanced breast cancer in Korea. In accordance with the Standards for Re-examination of New Drug, it is required to conduct a PMS. Post marketing surveillance is required to determine any problems or questions associated with Talzenna after marketing in Korea, with regard to the following clauses under conditions of general clinical practice. Therefore, through this study, effectiveness and safety of Talzenna will be observed.

Inclusion Criteria:

1. Patient scheduled to start treatment with Talzenna® based on the clinical judgment of their treating physician as specified in the Korean-Prescribing information (local label)
2. Evidence of a personally signed and dated informed consent document indicating that the patient (or a legally acceptable representative) has been informed of all pertinent aspects of the study.

Exclusion Criteria:

1. Patients with known hypersensitivity to Talzenna®, or to any of the excipients.
2. Breastfeeding
3. Any patients (or a legally acceptable representative) who does not agree that Pfizer and companies working with Pfizer use his/her information.

Talzenna® is indicated as monotherapy for the treatment of adult patients with breast cancer susceptibility gene (BRCA) mutated human epidermal growth factor receptor 2 (HER2)-negative locally advanced or metastatic breast cancer who have been treated with chemotherapy in the neoadjuvant, adjuvant, or advanced setting.

Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical\_trials/trial\_data\_and\_results/data\_requests.