For breast cancer, methylation has been noted in genes including BRCA1, p16, E-cadherin, H-cadherin, ATM, CST6, cyclin D2, PTEN, RASSF1A, APC, RARb2, GSTP1, ER, PR, as well as numerous other genes related to multiple pathways relevant for carcinogenesis [8,9,18]. Here, ESR1 is linked to breast cancer.