Low Ki67 expression was associated with pT1, luminal A, ER- and PR-positive, invasive lobular carcinoma and grade II tumours, while high Ki67 expression was associated with pT2, luminal B, HER2-, ER- and PR-negative (triple-negative), invasive ductal carcinoma and grade III tumours (P < 0.05). This evidence concerns the gene ERBB2 and invasive ductal breast carcinoma.