[CYP1A1 gene and GSTM1 gene polymorphism and the combined effects and risk of lung cancer: a meta-analysis].

BACKGROUND

Cytochrome P450A1 (CYP1A1) gene and glutathione S-transferase M1 (GSTM1) gene both have single nucleotide polymorphisms and effects on lung cancer. Currently, however, the risk of lung cancer due to the CYP1A1 and GSTM1 genes has no clear evidence. In this present study, we propose to research the combined effects of CYP1A1 gene and GSTM1 gene polymorphism and their risks to lung cancer.

METHODS

We conducted the study at different research areas and using various database, including PubMed, Embase, China Biology Medicine (CBM) and China National Knowledge Infrastructure (CNKI) last March 31, 2011. We calculated the adjusted odds ratio (OR) and 95% confidence interval (CI) for lung cancer in each study. Using STATA 10, a statistical program, we summarized the calculated estimates for the adjusted ORs and performed a meta-analysis.

RESULTS

The meta-analysis includes 15 research studies. The CYP1A1 IIe/Val genotype which carries a homozygous mutant type has a higher chance of risk to lung cancer than that which carries a homozygous mutant type and a heterozygous type when the GSTM1 carries a null genotype. As a result, OR was 3.18 (95%CI: 1.27-7.98), 1.45 (95%CI: 1.08-1.94), respectively. Meanwhile, the same conclusion was obtained for the CYP1A1 MspI genotype. The overall OR was 1.90 (95%CI: 1.00-3.58), 1.57 (95%CI: 1.23-2.00), respectively.

CONCLUSIONS

We discovered through our meta-analysis that the combined effects of CYP1A1 gene and GSTM1 gene polymorphism are significantly associated with an increased risk to lung cancer. We also found that homozygous mutant genotype of CYP1A1 has a higher chance of risk to lung cancer than the homozygous or heterozygous genotype.