We observed that the ER+ subtypes LumA and LumB are significantly less methylated comparing to the ER– breast cancer subtypes Basal-like, HER2 and 5NP (Kruskal–Wallis test, P = 1.19e–05 followed by Dunn‘s multiple comparison, Median values LumA 25.10, LumB 25.82, Basal-like 28.41, Her2 43.20, 5NP 34.71) (Figure 5).We did not observe any significant differences in methylation status within subtypes of the same ER status, indicating that decreased methylation occurs in both the ER+ subtypes, LumA and LumB, in a similar manner (Figure 5). This evidence concerns the gene ERBB2 and breast cancer.