(4–6) Also, the discovery of mutations like BRCA1/2 (breast cancer gene 1 and 2), PIK3CA (phosphatidylinositol-3-kinase [PI3K] catalytic subunit alpha), ESR1 (Estrogen Receptor 1), AKT (protein kinase B), and PTEN (phosphatase and tensin homolog) has further contributed to our ability to tailor treatments and, allowed a more targeted and effective approach to managing breast cancer. The gene discussed is ESR1; the disease is breast cancer.