title: Relationship of tobacco smoking  CYP1A1  GSTM1 gene polymorphism and esophageal cancer in Xi'an.
abstract: OBJECTIVE
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Epidemiology, Faculty of Preventive Medicine, Fourth Military Medical University Xi'an 710032, Shaanxi Province, China. wanganhui@hotmail.com
authors.forename: An-Hui
authors.initials: AH
authors.lastname: Wang
authors.forename: Chang-Sheng
authors.initials: CS
authors.lastname: Sun
authors.forename: Liang-Shou
authors.initials: LS
authors.lastname: Li
authors.forename: Jiu-Yi
authors.initials: JY
authors.lastname: Huang
authors.forename: Qing-Shu
authors.initials: QS
authors.lastname: Chen
mesh_terms: D016022:Case-Control Studies; D002681:China / Q000453:epidemiology; D019363:Cytochrome P-450 CYP1A1 / Q000235:genetics*; D004938:Esophageal Neoplasms / Q000453:epidemiology* / Q000235:genetics*; D005260:Female; D017353:Gene Deletion; D020022:Genetic Predisposition to Disease; D005838:Genotype; D005982:Glutathione Transferase / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology*
chemical_list: D019363:Cytochrome P-450 CYP1A1; D005982:Glutathione Transferase