By way of example, if not or incorrectly repaired by O(6)-Methylguanine-DNA-methyltransferase (MGMT), the NOC-specific DNA adduct O6-carboxymethyl-2′-deoxy-guanosine (O6-CMdG) would cause dramatic biological consequences, such as accumulating on the DNA of intestinal cells, promoting the shedding of colon cells, and leading to the early stage of CRC (95, 96). This evidence concerns the gene MGMT and colorectal carcinoma.