Impact of epoxide hydrolase 1 polymorphisms on lung cancer susceptibility in Asian populations.

Inconsistent association of microsomal epoxide hydrolase (mEH) polymorphisms (Tyr113His, His139Arg) and lung cancer susceptibility have been reported in earlier studies. This study was undertaken to assess if mEH Tyr113His and His139Arg represent risk factors for lung cancer in Asian population. We exhaustively searched multiple databases to identify all eligible studies. Odds ratios were calculated to estimate the strength of genetic associations. This meta-analysis finally combined 2,522 subjects for Tyr113His and 2,725 subjects for His139Arg. In the analysis of Tyr113His, the His/His genotype carriers were found to have 29 % higher risk of lung cancer compared to the Tyr/Tyr carriers (His/His vs. Tyr/Tyr, odds ratio, 1.29, 95 % confidence interval, 1.06-1.58). A significantly increased risk was also seen in His/His versus His/Tyr + Tyr/Tyr (odds ratio, 1.29, 95 % confidence interval, 1.07-1.55). Likewise, His139Arg demonstrated a significant association with lung cancer (Arg/His vs. His/His, odds ratio, 1.2 6, 95 % confidence interval, 1.06-1.49; odds ratio, 1.24, 95 % confidence interval, 1.05-1.46). Stratified analysis by ethnicity showed both of the polymorphisms were associated with lung cancer in Chinese populations. These results suggest that the genetic associations exist between mEH polymorphisms and lung cancer susceptibility in Asian populations.