PIK3CA Mutational Status Assessment

Inclusion Criteria: * Participant has a histologically and/or cytologically confirmed diagnosis of ER+ and/or PgR+ breast cancer by local laboratory. * Participant has HER2-negative breast cancer defined as a negative in situ hybridization test or an IHC status of 0, 1+ or 2+. If IHC is 2+, a negative in situ hybridization (Fluorescent in situ hybridization (FISH), Chromogenic in situ hybridization (CISH), or Silver-enhanced in situ hybridization (SISH)) test is required by local laboratory testing. * Participants should be at advanced or metastatic setting prior to treatment. * Written informed consent must be signed and dated by the patient and the investigator prior to inclusion. * Patients must be accessible for follow-up. Exclusion Criteria: • patients already treated with different treatments like chemotherapy, hormone therapy etc