title: A functional NQO1 609C>T polymorphism and risk of gastrointestinal cancers: a meta-analysis.
abstract: BACKGROUND
  The functional polymorphism (rs1800566) in the NQO1 gene, a 609C>T substitution, leading to proline-to-serine amino-acid and enzyme activity changes, has been implicated in cancer risk, but individually published studies showed inconclusive results.
  
  
  RESULTS
  We performed a meta-analysis of 20 publications with a total of 5,491 cases and 5,917 controls, mainly on gastrointestinal (GI) cancers. We summarized the data on the association between the NQO1 609C>T polymorphism and risk of GI cancers and performed subgroup analyses by ethnicity, cancer site, and study quality. We found that the variant CT heterozygous and CT/TT genotypes of the NQO1 609 C>T polymorphism were associated with a modestly increased risk of GI cancers (CT vs. CC: OR = 1.10, 95% CI = 1.01 - 1.19, P(heterogeneity) = 0.27, I(2) = 0.15; CT/TT vs. CC: OR = 1.11, 95%CI = 1.02 - 1.20, P(heterogeneity) = 0.14; I(2) = 0.27). Following further stratified analyses, the increased risk was only observed in subgroups of Caucasians, colorectal cancer in Caucasians, and high quality studies.
  
  
  CONCLUSIONS
  This meta-analysis suggests that the NQO1 609T allele is a low-penetrance risk factor for GI cancers. Although the effect on GI cancers may be modified by ethnicity and cancer sites, small sample seizes of the subgroup analyses suggest that further larger studies are needed, especially for non-colorectal GI cancers in Caucasians and GI cancers in Asians.
authors.affiliation: Department of Epidemiology, The University of Texas, M. D. Anderson Cancer Center, Houston, Texas, United States of America. hyu1@mdanderson.org
authors.forename: Hongping
authors.initials: H
authors.lastname: Yu
authors.forename: Hongliang
authors.initials: H
authors.lastname: Liu
authors.forename: Li-E
authors.initials: LE
authors.lastname: Wang
authors.forename: Qingyi
authors.initials: Q
authors.lastname: Wei
mesh_terms: D005770:Gastrointestinal Neoplasms / Q000235:genetics*; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005838:Genotype; D006801:Humans; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D012307:Risk Factors
chemical_list: D016660:NAD(P)H Dehydrogenase (Quinone); C447479:NQO1 protein, human