ESR1 and triple-negative breast carcinoma: The loss of E-cad expression has been found to be significantly associated with a lack of estrogen receptor (ER) expression, the expression of cytokeratins 5/6 and/or epidermal growth factor receptor (EGFR), and a basal-like phenotype (or triple-negative breast cancer, TNBC) in breast cancer [12, 13].