To validate the potential of the five-miRNA signature as a predictor of DSS of patients with BC, the entire TCGA BC dataset was stratified by cancer stage, age, and molecular subtype; BC cases were split into three age subgroups (≤ 40, 41–60, and ≥ 61 years old), four lymph node status subgroups (N0, N1, N2, and N3), four tumor size subgroups (T1, T2, T3, and T4), and five molecular subtype subgroups (LumA-like, LumB-like, HER2, basal-like, and normal-like). Here, ERBB2 is linked to breast cancer.