According to ASCO guideline and the latest St Gallen consensus, triple-negative breast cancer (TNBC) occurs only if there is no expression of estrogen receptor (ER-negative), progesterone receptor (PR-negative), and there is neither expression nor amplification of human epidermal growth factor receptor 2 (HER2-negative) in a tumor [1, 2]. This evidence concerns the gene ESR1 and triple-negative breast carcinoma.