Consistent with prior epidemiologic studies in the US, the most common breast cancer subtype within this cohort was HR+, HER2- (69.6%), followed by TNBC (10.5%), HR+, HER2+ (9.6%), and HR-, HER2+ (4.0%); there were 21,788 (6.4%) patients with EBC, and unknown HR, HER2 status (S1 Fig). This evidence concerns the gene ERBB2 and breast cancer.