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.

System review and metaanalysis of the relationships between five metabolic gene polymorphisms and colorectal adenoma risk.

The relationships between some metabolic (including EPHX1, GSTs and NQO1) gene polymorphisms and colorectal adenoma (CRA) risk have been commonly studied, and no conclusions are available up to now. Therefore, we quantitatively studied the relationships by a metaanalysis. The databases of Medline and Embase were retrieved updated to June 15th, 2011. Crude or adjusted odds ratio (crude OR or adjusted OR) and 95% confidence interval (95%CI) were calculated to present the strength of the associations. Overall, nine case-control studies for EPHX1 Tyr113His and His139Arg, five case-control studies for GSTM1, four studies for GSTP1 Ile105Val, two studies for GSTP1 Ala114Val, six studies for GSTT1 and four studies for NQO1 Pro187Ser were included in this metaanalysis. The results of combined analyses indicated that EPHX1 Tyr113His and His139Arg, GSTT1, GSTM1, GSTP1 Ile105Val and Ala114Val were not associated with CRA risk [crude OR (95%CI): 0.98 (0.90-1.07) and P ( z-test) = 0.65 for EPHX1 His carriers vs. Tyr/Tyr; 1.05 (0.97-1.15) and P ( z-test) = 0.21 for EPHX1 Arg carriers vs. His/His; 1.05 (0.92-1.20) and P ( z-test) = 0.47 for GSTT1 Null vs. Present; 1.01 (0.90-1.13) and P ( z-test) = 0.90 for GSTM1 Null vs. Present; 1.04 (0.92-1.17) and P ( z-test) = 0.56 for G carriers vs. AA for GSTP1 Ile105Val; 0.88 (0.70-1.11) and P ( z-test) = 0.28 for T carriers vs. CC for GSTP1 Ala114Val]. In contrast, Ser allele of NQO1 Ser187Pro might be a modest risk factor for CRA development [1.19 (1.06-1.33) and P ( z-test) = 0.003 for Ser carriers vs. Pro/Pro]. To get more precise evidences, adjusted ORs (95%CI) for EPHX1 Tyr113His, His139Arg, GSTP1 Ile105Val and NQO1 Ser187Pro were also calculated based on adjusted ORs (95%CIs) reported in primary studies. The results still indicated that EPHX1 Tyr113His, His139Arg and GSTP1 Ile105Val were not associated with CRA risk except for NQO1 Ser187Pro. When subgroup analyses were performed for population-based case-control studies or studies in HWE for EPHX1 Tyr113His and His139Arg, and NQO1 Ser187Pro polymorphisms, the results were persistent. Although with modest limitations and biases, this metaanalysis suggests that EPHX1 Tyr113His and His139Arg, GSTT1, GSTM1, GSTP1 Ile105Val and Ala114Val polymorphisms may be not risk factors for CRA development, while Ser allele of NQO1 Ser187 Pro may be a modest risk factor for CRA development, and may be used with other genetic markers for screening CRA in the future.