Objectively, Perou et al. [44] and Sørlie et al. [45] have revealed that HER2+ patients displayed a very low expression level of ER/PR than those of HER2- patients, indicating that patients with ER/PR+ HER2+ breast carcinoma are likely to resist hormonal therapy than those of ER/PR- HER2+ [35, 41]. This evidence concerns the gene ESR1 and breast carcinoma.