ESR1 and triple-negative breast carcinoma: Triple-negative breast carcinoma (TNBC) is a subtype of breast carcinoma with hormone receptor immunohistochemistry (IHC) stains of less than 1% for estrogen receptors (ER) and progesterone receptors (PR) and is devoid of HER2 protein overexpression or HER2 gene amplification (or both) (Bergin and Loi, 2019).