XRCC1 and colorectal carcinoma: However, it has been indicated that the polymorphism of XRCC1 gene, including the Arg194Trp which is a substitution of arginine to tryptophan at position 194 of XRCC1, also plays an important role in affecting the susceptibility, prognosis, and therapy outcome of the clinical CRC patient with platinum/5-FU treatment [37,38].