With respect to an association with HER2 status alone, current use of any type of MHT was found to be associated with a significant elevation in the risk of HER2- breast cancer (aOR = 2.20, 95%CI: 1.36–3.55), but not HER2+breast cancer, although it should be noted that in the current analysis the odds ratios by HER2 expression were not significantly different (p(het) = 0.183). This evidence concerns the gene ERBB2 and breast carcinoma.