Association of CYP1A1 gene polymorphism and susceptibility to lung cancer: a case-control study

Objectives: To investigate the relationship between the metabolic activation enzyme cytochrome P4501A1 gene (CYP1A1) polymorphism and lung cancer in the Chinese population. Methods: Case-control study was used to investigate the distribution frequencies of the CYP1A1 polymorphic genotypes in 98 lung cancer patients and 98 healthy subjects and analyze the relationship between gene polymorphism and susceptibility to lung cancer. Results: Significant differences were observed (x2=13.57, P<0.05) between the case group and the control group in terms of the gene frequency distributions of the three CYP1A1 genotypes (the mutant, the heterozygous genotype and the wild type). For CYP1A1 gene, a lower risk of developing lung cancer was observed in subjects carrying Ile/ Ile genotype than subjects carrying Ile/Val or Val/Val genotype [OR: 0.37 (95% CI 0.20-0.70, x2=9.67, P<0.05); 0.27 (95% CI 0.11-0.65, x2=9.03, P<0.05)], which probably indicated that Ile/Ile genotype was a protective factor against lung cancer. In the smoking group, the odds ratio (OR) for susceptibility of Ile/Val or Val/Val subjects to lung cancer was 3.1 compared with Ile/Ile subjects, which was statistically significant. Conclusions: A relationship is found between CYP1A1 gene polymorphism and lung cancer in the Chinese population. The mutant Val allele is probably the susceptible genotype for lung cancer in the Chinese population. Val allele mutation presumably causes lung cancer in coordination with smoking.