This is a prospective, multicenter, open-label, non-comparative, non-interventional, observational study to assess te safety and effectiveness of Piqray in the real-world setting

The observation duration will be up to 24 weeks after enrollment, which is sufficient to provide adequate information about the safety and effectiveness of Piqray. If the subject does not return for a follow-up visit or stops taking Piqray for any reason, all data collected until the date of the last contact of the subject will be used. Patients will be followed up (safety follow up) for 30 days afetr either 24 weeks-treatment or early withdrawal.

Inclusion Criteria:

Subjects eligible for this study must meet all of the following criteria:

1. Postmenopausal women and men who have a confirmed diagnosis of hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative, PIK3CA mutated, advanced or metastatic breast cancer.
2. Patients who have progressed on prior endocrine based therapy and are going to start Piqray treatment for the first time in accordance with the locally approved label.
3. Patients who are willing to provide written informed consent

Exclusion Criteria:

Subjects eligible for this study must not meet the following criteria:

1. Patients with contraindication according to prescribing information for Piqray in Korea.

   - Severe hypersensitivity to Piqray or to any of its components

2. Female subjects who are pregnant and nursing (lactating)

3. Patients who are sexually active but not willing to follow contraceptive precautions during taking Piqray.

4. Participants who receive or are going to receive any investigational medicine during surveillance period.

Patients who are going to receive Piqray per locally approved label are eligible and will be prescribed with Piqray under routine medical practice.