Association between CYP2E1 genetic polymorphisms and lung cancer risk: a meta-analysis.

Genetic variations in metabolic genes are thought to modify the metabolic process of carcinogens and are suggested to be related to cancer risk. However, epidemiological results are not always consistent. In this meta-analysis, we assessed reported studies of associations between polymorphisms of CYP2E1 RsaI/PstI and DraI, and the risk of lung cancer. We found decreased lung cancer risk among subjects carrying CYP2E1 RsaI/PstI c1/c2 and c1/c2+c2/c2 genotype [odds ratio (OR)=0.80, 95% confidence interval (CI): 0.72-0.89 and OR=0.82, 95% CI: 0.72-0.93, respectively], using 4436 cases and 6385 controls from 26 studies. We also observed a decreased lung cancer risk among subjects carrying c1/c2 and c1/c2+c2/c2 genotypes in the Asian population and on the basis of population control in stratified analysis. We found a protective effect of the CYP2E1 DraI CC and CD+CC polymorphisms for lung cancer (OR=0.58, 95% CI: 0.41-0.81 and OR=0.84, 95% CI: 0.73-0.96, respectively). The meta-analysis suggests that CYP2E1 RsaI/PstI and DraI polymorphisms may affect the susceptibility of lung cancer, and a study with a larger sample size is needed to further evaluate gene-environment interaction on CYP2E1 polymorphisms and lung cancer risk.