XRCC1 and cancer: However, the frequency of the XRCC1 399Gln allele (25%) was similar to that reported in other Japanese populations,13,38 and the frequency of the XRCC1 194Trp allele (32%) was consistent with the results of a study in Japanese (30%).39 Information on the frequency of the XRCC1 280His allele in a Japanese population was not available because, to our knowledge, the present study is the first to report an association between the XRCC1 Arg280His polymorphism and cancer risk in Japan.