A meta-analysis on XRCC1 and XRCC3 polymorphisms and colorectal cancer risk

Studies on polymorphism of X-ray repair cross-complementing group 1 (XRCC1), group 3 (XRCC3), and colorectal cancer risk are inconclusive. The purpose of this study is to evaluate the role of XRCC1 R399Q, R194W, and XRCC3 T241M genotypes in colorectal cancer susceptibility. We performed a meta-analysis on all available studies that provided 3,514/4,686 cases/controls for R399Q, 2,767/3,907 cases/controls for R194W and 3,183/3,926 cases/controls for T241M. Overall, no apparent effects of 194 W allele compared to 194R on colorectal cancer risk were found in all subjects and subgroups (Asians and Caucasians). Insignificant effects were also found under other genetic contrasts (homologous contrast, dominant model, and recessive model). The same pattern of results was produced in T241M polymorphism. The 399Q allele compared to 399R showed no significant association with colorectal cancer risk in all subjects and subgroups. However, protective effects of 399QQ genotype were observed under recessive model (QQ/QR + RR) [P = 0.02, OR = 0.84, 95% CI (0.72, 0.97)] and homozygote contrast (QQ/RR) [P = 0.01, OR = 0.81; 95% CI (0.69, 0.95)] in all subjects. Results suggested that 399Q allele might act as a recessive allele in its association with colorectal cancer.