XRCC1 and nasopharyngeal carcinoma: Multivariate regression analyses showed that males carrying the XRCC1 194Trp/Trp genotype had a reduced risk of developing NPC (OR = 0.32; 95% CI, 0.14–0.70; P = 0.004) compared with those carrying the Arg/Arg genotype; risk in males was not effected by the 194Arg/Trp heterozygous genotype (OR = 0.77; 95% CI, 0.54–1.10).