Objectives: To assess the association between the variant of Cytochrome P450 2A6 whole gene deletion (CYP2A6*4) polymorphism and risk of lung cancer.
Methods: Two investigators independently searched the PubMed, Elsevier, EMBASE, Web of Science, Wiley Online Library and Chinese National Knowledge Infrastructure (CNKI). Pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) for CYP2A6*4 and lung cancer were calculated in a fixed-effects model (the Mantel-Haenszel method) and a random-effects model (the DerSimonian and Laird method) when appropriate.
Results: This meta-analysis included seven eligible studies, which included 2524 lung cancer cases and 2258 controls (cancer-free). Overall, CYP2A6*4 was associated with the risk of lung cancer (allele*4 vs. allele non-*4, pooled OR = 0.826, 95% CI = 0.725-0.941, P-value = 0.004). When stratifying for population, significant association was observed in Asian (additive model, pooled OR = 0.794, 95% CI = 0.694-0.909, P-value = 0.001; dominant model, pooled OR = 0.827, 95% CI = 0.709-0.965, P-value = 0.016; recessive model (pooled OR = 0.444, 95% CI = 0.293-0.675, P-value <0.0001). In the overall analysis, a comparably significant decrease in the frequency of *4/*4 genotype was detected between cases and controls in Asian while no *4/*4 genotype was detected in Caucasian in collected data.
Conclusion: This meta-analysis suggests that the CYP2A6*4 polymorphism is associated with susceptibility of lung cancer in Asian. The whole gene deletion of CYP2A6 may decrease the risk of lung cancer in Asian samples.