X-ray repair cross-complementing group 1 codon 399 polymorphism and lung cancer risk: an updated meta-analysis.

Many epidemiologic studies have investigated the association between x-ray repair cross-complementing group 1 gene (XRCC1) codon 399 polymorphism and lung cancer risk, but the results were inconsistent. We performed a meta-analysis of 46 studies on XRCC1 codon 399 polymorphism and lung cancer risk published before June 2013. In general population, the M allele and MM genotype were associated with increased risk of lung cancer compared with C allele and CC genotype, and the ORs were 1.06 (95% CI 1.01-1.12) and 1.19 (95% CI 1.05-1.34), respectively. When it was stratified according to Asian population, the association between XRCC1 codon 399 polymorphism and lung cancer risk was further strengthened. The ORs of comparison between M vs. C, MM vs. CC, and MM vs. CM + CC were 1.14 (95% CI 1.03-1.26), 1.41 (95% CI 1.11-1.78), and 1.38 (95% CI 1.12-1.71), respectively. The association between codon 399 polymorphism and lung cancer risk in nonsmoking Chinese women was stronger than any other subgroups. However, no associations were found in the Caucasian and African population. This meta-analysis has demonstrated that codon 399 polymorphism of XRCC1 gene might contribute to individual's susceptibility to lung cancer in Asian population, and especially in nonsmoking Chinese women. Future studies focused on interactions between combined genes and environmental risk factors are warranted.