Triple‐negative breast cancer (TNBC), characterized by lack of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) expression, accounts for 15%–20% of all breast cancer cases and is associated with poor prognosis, high recurrence rate, and limited treatment options [1–4]. The gene discussed is ESR1; the disease is breast carcinoma.