Triple-negative breast cancer (TNBC) represents 15% of breast carcinomas, a particularly aggressive and heterogeneous subtype defined by the absence of the three primary breast cancer biomarkers - estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2, also known as ERBB2). This evidence concerns the gene ESR1 and triple-negative breast carcinoma.