Certain genes showed relatively high DNA methylation levels in both biopsies and epithelial cells in adenoma and cancer cases, as PRIMA1, SFRP1, SFRP2, MAL, SOCS3, CYP27B1, COL1A2 and SULT1A1. THBS2 showed high methylation levels across all samples. This evidence concerns the gene SFRP2 and cancer.