Molecular targets in breast cancer that dictate treatment options depend on the receptor-based classification, which include estrogen receptor α (ERα)-positive, progesterone receptor (PR)-positive, human epidermal growth factor receptor 2 (HER2)-enriched, and triple-negative breast cancer (TNBC) that do not express any of these three receptors (6). The gene discussed is ESR1; the disease is breast carcinoma.