TMEFF2 and ductal breast carcinoma in situ: In breast cancer, TMEFF2 promoter methylation increases progressively along the potential developmental path of invasive ductal carcinoma (IDC) from the preinvasive lesions like flat epithelial atypia (FEA), atypical ductal hyperplasia (ADH) and ductal carcinoma in situ (DCIS) [29,30].