Triple-negative breast cancer (TNBC) accounts for 12–20% of all breast cancer cases and is characterized by a lack of estrogen receptor (ER) and progesterone receptor (PR) expression, combined with an absence of both overexpression and amplification of the human epidermal growth factor receptor-2 (HER-2) gene (2). The gene discussed is ESR1; the disease is triple-negative breast carcinoma.