Mammary carcinomas lacking the expression of ER, PR, and HER2 are known as Triple-negative breast cancers and are furtherly subclassified into basal-like carcinomas when expressing basal/myoepithelial markers: cytokeratins CK5/6, or CK14 and/or the EGFR [22,32]. The gene discussed is ESR1; the disease is breast carcinoma.