CYP2A6 deletion polymorphism is associated with decreased susceptibility of lung cancer in Asian smokers: a meta-analysis.

Cytochrome P450 2A6 (CYP2A6) is an enzyme involved in the metabolism of some tobacco carcinogens, which is an important risk factor of lung cancer. Among CYP2A6 allelic variants, CYP2A6*4 presents a whole gene deletion that accounts for the majority of poor metabolizer. In this study, a meta-analysis was performed to assess the association between CYP2A6*4 and risk of lung cancer. Literature searches were conducted to identify peer-reviewed manuscripts published up to December 20, 2012. Pooled odds ratios (ORs) and 95 % confidence intervals (95 % CIs) were calculated in a fixed-effects model and a random-effects model when appropriate. Eight eligible studies with 3,203 lung cancer cases and 2,839 controls were included in this study. Overall, no significant association was observed in CYP2A6*4 with the risk of lung cancer under any genetic model for all samples after correction. However, subgroup analysis showed that significant associations were observed in Asian with pooled OR (95 %CI) of 0.761 (0.672-0.861) for allele comparison, 0.769 (0.668-0.886) for dominant model, and 0.522 (0.359-0.760) for recessive model. Furthermore, after stratifying Asian samples according to smoking status, significant associations were only observed in smokers with pooled OR (95 %CI) of 0.713 (0.607-0.838) for allele comparison, 0.720 (0.596-0.869) for dominant model, and 0.444 (0.275-0.715) for recessive model. This meta-analysis suggests that the CYP2A6*4 polymorphism was associated with susceptibility of lung cancer for smokers in Asian. The whole gene deletion of CYP2A6 might decrease the risk of tobacco-related lung cancer in Asian.