title: Meta-analysis of association studies of CYP1A1 genetic polymorphisms with digestive tract cancer susceptibility in Chinese.
abstract: BACKGROUND
  A great number of studies have shown that cytochrome P450 1A1 (CYP1A1) genetic polymorphisms, CYP1A1 Msp I and CYP1A1 Ile/Val, might be risk factors for digestive tract cancers, including esophageal cancer (EC), gastric cancer (GC), hepatic carcinoma (HC), as well as colorectal cancer (CC), but the results are controversial. In this study, a meta-analysis of this literature aimed to clarify associations of CYP1A1 genetic polymorphisms with digestive tract cancer susceptibility in Chinese populations.
  
  
  METHODS
  Eligible case-control studies published until December 2013 were retrieved by systematic literature searches from PubMed, Embase, CBM, CNKI and other Chinese databases by two investigators independently. The associated literature was acquired through deliberate search and selection based on established inclusion criteria. Fixed- effects or random-effects models were used to estimate odds ratios (ORs and 95%CIs). The meta-analysis was conducted using Review Manager 5.2 and Stata 12.0 softwares with stability evaluated by both stratified and sensitivity analyses. Moreover, sensitivity analysis and publication bias diagnostics confirmed the reliability and stability.
  
  
  RESULTS
  Eighteen case control studies with 1, 747 cases and 2, 923 controls were selected for CYP1A1 MspI polymorphisms, and twenty case-control studies with 3, 790 cases and 4, 907 controls for the CYP1A1 Ile/ Val polymorphisms. Correlation associations between CYP1A1 Ile/Val polymorphisms and digestive tract cancers susceptibility were observed in four genetic models in the meta-analysis (GG vs AA:OR= 2.03, 95%CI =1.52- 2.72; AG vs AA: OR=1.26, 95%CI =1.07-1.48; [ GG+AG vs AA] :OR =1.42, 95%CI=1.20-1.68, [GG vs AA+AG ]:OR=1.80, 95%CI =1.40-2.31). There was no association between CYP1A1 Msp I polymorphisms and digestive tract cancer risk. Subgroup analysis for tumor type showed a significant association of CYP1A1 Ile/Val genetic polymorphisms with EC in China. However, available data collected by the study failed to reveal remarkable associations of GC or HC with CYP1A1 Ile/Val genetic polymorphisms and EC, GC or CC with CYP1A1 MspI genetic polymorphisms.
  
  
  CONCLUSIONS
  Our results indicated that CYP1A1 Ile/Val genetic polymorphisms, but not CYP1A1 Msp I polymorphisms, are associated with an increased digestive tract cancer risk in Chinese population. Additional well-designed studies, with larger sample size, focusing on different ethnicities and cancer types are now warranted to validate this finding.
authors: Department of Gastroenterology, The First People's Hospital of Chongqing New North Zone, Chongqing, China E-mail : jiangz1753@163.com.
authors: Chang
authors: C
authors: Liu
authors: Zheng
authors: Z
authors: Jiang
authors: Qian-xi
authors: QX
authors: Deng
authors: Ya-nan
authors: YN
authors: Zhao
mesh_terms: D044466:Asian People / Q000235:genetics*; D016022:Case-Control Studies; D019363:Cytochrome P-450 CYP1A1 / Q000235:genetics*; D004067:Digestive System Neoplasms / Q000209:etiology* / Q000235:genetics*; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005838:Genotype; D006801:Humans; D011110:Polymorphism, Genetic / Q000235:genetics*; D012306:Risk
chemical_list: C569463:CYP1A1 protein, human; D019363:Cytochrome P-450 CYP1A1