ESR1 and triple-negative breast carcinoma: Triple negative breast cancer (TNBC), which accounts for 10–20% of all breast cancer (BC) cases, is defined by the lack of expression of hormone receptors, estrogen receptor (ER) and progesterone receptor (PgR), and human epidermal growth factor receptor 2 (HER2) [1], and is associated with poor prognosis [2].