Angiotensin-converting enzyme insertion/deletion gene polymorphism and lung cancer risk: A meta-analysis.

OBJECTIVE

Angiotensin-converting enzyme (ACE) I/D polymorphism has been reported to be associated with lung cancer, but the results of previous studies are conflicting. The present study was designed to investigate the association between this polymorphism and the risk of lung cancer using a meta-analysis of the published studies.

METHODS

Two investigators independently searched the PubMed, Embase and CNKI databases. This meta-analysis covered six case-control studies, including 807 lung cancer patients and 816 healthy controls.

RESULTS

The results of this meta-analysis based on all the studies showed no significant association between ACE I/D gene polymorphism and lung cancer risk (DD vs II: OR = 1.18, 95% CI = 0.68-2.04; DI vs II: OR = 0.93, 95% CI = 0.56-1.53; DD+DI vs II: OR = 1.01, 95% CI = 0.68-1.50; DD vs II+DD: OR =1.11, 95% CI = 0.73-1.71). In the subgroup analysis by race and the larger studies (n > 200 participants), no significant associations between the ACE I/D polymorphism and risk of lung cancer were indicated. However, when the analyses were restricted to small studies (n ≤ 200 participants), a significantly higher risk was observed (DD vs II: OR = 2.57, 95% CI = 1.24-5.30).

CONCLUSIONS

This meta-analysis suggests that the ACE gene I/D polymorphism may not be associated with the risk of lung cancer, and the observed increase in the risk of lung cancer may be due to small-study bias.