PIK3CA Mutational Status Assessment

This study is analyzing tumor samples from patients with advanced hormone receptor-positive, HER2-negative breast cancer to determine if a specific gene mutation (in the PIK3CA gene) is present, which could guide eligibility for targeted therapies like alpelisib. **You may be eligible if...** - You have a confirmed diagnosis of hormone receptor-positive (ER+ and/or PR+), HER2-negative breast cancer - Your cancer is advanced or has spread to other parts of the body - You have not yet started treatment for advanced disease - You are accessible for follow-up **You may NOT be eligible if...** - You have already received treatment for your advanced or metastatic breast cancer - You are unable to provide written consent Talk to your doctor to see if this trial is right for you.