ERBB2 and breast cancer: DNA methylation levels of TfR1 were obviously decreased in both female and male BC patients; BC patients with stage 1, 2 and 3 disease; different subtypes (luminal, HER2-positive and TNBC); different nodal metastasis statuses (N0, N1, N2 and N3); different ages (21–40, 41–60, 61–80 and 81–100 years); different races (Caucasian, African-American, and Asian); and different menopause statuses (pre-menopausal, peri-menopausal and post-menopausal) (Figure 7A and Supplementary Figure 3A).