NAD(P)H quinone oxidoreductase 1 (NQO1) genetic C609T polymorphism is associated with the risk of digestive tract cancer: a meta-analysis based on 21 case-control studies.

The relationships between the NAD(P)H quinone oxidoreductase 1 (NQO1) C609T polymorphism and the risk of digestive tract (DT) cancer are controversial. Therefore, we performed a meta-analysis to assess the relationships. The databases of Medline, Embase, and WanFang (updated to 15 May 2011) were reviewed. Odds ratios and 95% confidence intervals were calculated to assess the strength of the associations. Overall, 21 individual case-control studies in 20 papers with 5340 cases and 5911 controls were included in this meta-analysis. The results of combined analyses indicated that the T allele of NQO1 C609T was significantly associated with increased risk of DT cancer [odds ratio (95% CI): 1.58 (1.22-2.07) for TT vs. CC and 1.13 (1.06-1.22) for T carriers vs. C carriers]. Subgroup analyses for different types of cancers indicated that the T allele was significantly associated with an increased risk of gastric cancer [1.19 (1.13-1.47) for T carriers vs. C carriers], but not with esophageal cancer [1.05 (0.86-1.27) for T carriers vs. C carriers] and colorectal cancer [1.09 (0.98-1.21) for T carriers vs. CC]. Subgroup analyses for ethnicities and countries indicated that the T allele was associated with risk of DT cancer among Europeans [1.52 (1.05-2.19) for TT vs. CC] and Asians [1.52 (1.05-2.19) for TT vs. CC], and German, Indian, and Chinese populations but not among English and Japanese populations. In addition, subgroup analyses also indicated that the T allele was significantly associated with risk of DT cancer in studies with large and small sample sizes and in population-based studies, but not in hospital-based studies. This meta-analysis suggests that NQO1 C609T is significantly associated with risk of DT cancer among both Europeans and Asians, especially gastric cancer. Because of the limited number of cases and controls in the subgroup analyses, more well-designed studies with a large sample of participants are needed to verify our findings.