Concerning tumour location, MGMT, SEPT9, and RASSF1A methylation levels were significantly higher in colon cancer (proximal and distal) patients (P = 0.000, P = 0.000 and P = 0.002, respectively), compared to CRN, whereas APC, MGMT and SEPT9 displayed significantly higher promoter methylation levels in rectal cancer (P = 0.018, P = 0.0003 and P = 0.002, respectively). This evidence concerns the gene RASSF1 and rectal cancer.