Triple‐negative breast cancer (TNBC) comprises ≈10–20% of breast cancer cases and is characterized by the absence of estrogen receptor (ER) expression, progesterone receptor (PR) expression, and human epidermal growth factor receptor 2 (HER2) amplification.[1] Compared to other subtypes, TNBC exhibits clinical characteristics of earlier onset, higher metastatic potential, and worse clinical outcomes.[2] Due to the limited progress in targeted therapies, chemotherapy remains the predominant treatment for TNBC patients. The gene discussed is ESR1; the disease is breast cancer.