In the United States, among the BC subtypes, 70% of cases are distributed in hormonal receptor-positive and human epidermal growth factor receptor 2-negative (HR+/HER2-), 10% are hormonal receptor-negative and HER2- (HR-/HER2-), 9% are HR+/HER2+, 4% are HR-/HER2+, and 7% are unknown cases.114. This evidence concerns the gene ERBB2 and breast cancer.