ERBB2 and breast cancer: A significant difference in CDH13 methylation was observed between BC molecular subtypes LUM A vs. HER2 (average methylation level 6.54% vs. 17.3%, P = 0.0116; 17.0% of methylated samples vs. 43.3%, P = 0.0183) and HER2 vs. TNBC (average methylation level 17.3% vs. 7.09%, P = 0.0234).