XRCC1 and colorectal cancer: For the XRCC1 399Gln allele, 2 previous studies showed an increased risk of colorectal cancer,9,10 while other case-control studies showed no positive association with the that allele,11–17 including a small study in Japan.13 Discrepant findings have also been reported for the XRCC1 Arg194Trp and Arg280His polymorphisms.