title: NAD(P)H:quinone oxidoreductase 1 (NQO1) Pro187Ser polymorphism and the risk of lung, bladder, and colorectal cancers: a meta-analysis.
abstract: NAD(P)H:quinone oxidoreductase 1 (NQO1) is a cytosolic enzyme that catalyzes the two-electron reduction of quinoid compounds into hydroquinones, their less toxic form. A sequence variant at position 609 (C --> T) in the NQO1 gene encodes an enzyme with reduced quinone reductase activity in vitro and thus was hypothesized to affect cancer susceptibility. We conducted meta-analyses focusing on three cancer sites (lung, bladder, and colorectum) to summarize the findings from the current literature and to explore sources of heterogeneity.
  
  
  RESULTS
  There is no clear association between the NQO1 Pro187Ser polymorphism and lung cancer risk in the three ethnic groups examined: odds ratio (OR(White)) C/T + T/T versus C/C = 1.04 [95% confidence interval (95% CI), 0.96-1.13], OR(Asian) = 0.99 (95% CI, 0.72-1.34), and OR(Blacks) = 0.95 (95% CI, 0.66-1.36). However, a modestly increased risk was suggested for the variant homozygotes in whites (OR T/T versus C/C, 1.19; 95% CI, 0.94-1.50). Analysis excluding one outlier study suggested the variant allele may be associated with reduced lung cancer risk in Asians. Meta-analyses for bladder and colorectal cancer suggested a statistically significant association with the variant genotypes in whites. In stratified analyses, the NQO1 Pro187Ser variant genotypes were associated with slightly increased lung cancer risk in white ever smokers but not in white never smokers and were mainly associated with a reduced risk of lung adenocarcinoma but not squamous cell carcinoma in Asians.
  
  
  CONCLUSIONS
  Results from our meta-analyses suggest that the variant NQO1 Pro187Ser genotype may affect individual susceptibility to lung, bladder, and colorectal cancer. Such effects of the NQO1 polymorphism seem to be modified by ethnicity and smoking status.
authors.affiliation: Gene-Environment Epidemiology Group, IARC, 150, cours Albert Thomas, 69372 Lyon Cedex 08, France. hashibe@iarc.fr.
authors.forename: Chun
authors.initials: C
authors.lastname: Chao
authors.forename: Zuo-Feng
authors.initials: ZF
authors.lastname: Zhang
authors.forename: Julien
authors.initials: J
authors.lastname: Berthiller
authors.forename: Paolo
authors.initials: P
authors.lastname: Boffetta
authors.forename: Mia
authors.initials: M
authors.lastname: Hashibe
mesh_terms: D016009:Chi-Square Distribution; D015179:Colorectal Neoplasms / Q000208:ethnology / Q000235:genetics*; D005838:Genotype; D006801:Humans; D008175:Lung Neoplasms / Q000208:ethnology / Q000235:genetics*; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000235:genetics*; D011110:Polymorphism, Genetic; D012907:Smoking / Q000009:adverse effects; D001749:Urinary Bladder Neoplasms / Q000208:ethnology / Q000235:genetics*
chemical_list: D016660:NAD(P)H Dehydrogenase (Quinone); C447479:NQO1 protein, human