In order to independently validate IRF9 as a prognostic marker, we analyzed baseline IRF9 expression in an adjuvant cohort of 414 breast cancer patients of mixed breast cancer subtypes (ER±  luminal A and B, HER2+, and TNBC) where chemotherapy was administered subsequent to tumor resection (Supplementary Table 2). This evidence concerns the gene ERBB2 and neoplasm.