Published online Feb 15, 2002. doi: 10.3748/wjg.v8.i1.49
Revised: September 10, 2001
Accepted: November 15, 2001
Published online: February 15, 2002
AIM: To analyze the association of tobacco smoking, polymorphism of CYP1A1 (7th exon) and GSTM1 genotype and esophageal cancer(EC) in Xi’an.
METHODS: A hospital based case-control study, with molecular epidemiological method, was carried out. Polymorphism of CYP1A1 and GSTM1 of samples from 127 EC cases and 101 controls were detected by PCR method.
RESULTS: There were no significant difference of age and gender between cases and controls. Tobacco smoking was the main risk factor(OR = 1.97; 95%CI = 1.12-3.48) for EC in Xi’an. The proportions of CYP1A1 Ile/Ile, Ile/Val and Val/Val gene types in cases and controls was 19.7%, 45.7%, 34.6% and 30.7%, 47.5%, 21.8% respectively (P = 0.049).Individuals with CYP1A1 Val/Val genotype compared to those with CYP1A1 Ile/Ile genotype had higher risk for EC increased (OR = 2.48, 95%CI = 1.12-5.54). The proportions of GSTM1 deletion genotype in cases and controls were 58.3% and 43.6% (OR = 1.81, 95%CI = 1.03-3.18, P = 0.028). Analysis of gene-environment interaction showed that tobacco smoking and CYP1A1 Val/Val genotype; tobacco smoking and GSTM1 deletion genotype had synergism interaction respectively. Analysis of gene-gene interaction did not find synergistic interaction between these two genes. But in GSTM1 deletion group,there was significant difference of distribution of CYP1A1 genotype between cases and controls (P = 0.011).
CONCLUSION: CYP1A1 Val/Val and GSTM1 deletion genotypes are genetic susceptibility biomarkers for EC. The risk increases, when person with CYP1A1 Val/Val and/or GSTM1 deletion genotype. And these two-metabolic enzymes seem to have interactions with tobacco smoking, in which the mechanism still needs further study.