In order to test whether the individual polymorphisms in the two DNA repair genes might interact and modify the risk of developing gastric cancer, ORs and 95% CIs were estimated for the combined genotypes of XRCC1 Arg399Gln and XPD Lys751Gln polymorphisms; however, no effect modifications were observed by these polymorphisms in the current study (P interaction = 0.793) Table 3. The gene discussed is XRCC1; the disease is gastric cancer.