Association between NAD(P)H:quinone oxidoreductase 1 rs1800566 polymorphism and risk of bladder cancer

quinone oxidoreductase 1 (NQO1) rs1800566 (Pro187Ser) is a functional polymorphism which leads to a proline-to-serine amino acid substitution at codon 187 in the NQO1 protein and enzyme activity changes. NQO1 rs1800566 polymorphism was implicated to be associated with a risk of bladder cancer, but published studies showed inconclusive results. We performed a meta-analysis of nine publications with a total of 2,661 cases and 2,738 controls on the association between NQO1 rs1800566 polymorphism and risk of bladder cancer. Data were extracted from those included studies, and the pooled odds ratio (OR) with the corresponding 95% confidence interval (95% CI) was calculated to assess the association. We found that there was no association between NQO1 rs1800566 polymorphism and risk of bladder cancer under all four genetic models (Ser vs. Pro, OR = 1.06, 95% CI = 0.97-1.16, P = 0.21, I(2) = 31%; SerSer vs. ProPro, OR = 1.12, 95% CI = 0.89-1.42, P = 0.33, I(2) = 44%; SerSer/ProSer vs. ProPro, OR = 1.08, 95% CI = 0.96-1.21, P = 0.20, I(2) = 27%; SerSer vs. ProPro/ProSer, OR = 1.06, 95% CI = 0.85-1.32, P = 0.59, I(2) = 36%). Meta-analysis of those eight studies from Europeans also showed that there was no association between NQO1 rs1800566 polymorphism and risk of bladder cancer under all four genetic models (Ser vs. Pro, OR = 1.02, 95% CI = 0.93-1.13, P = 0.66, I(2) = 20%; SerSer vs. ProPro, OR = 0.99, 95% CI = 0.75-1.30, P = 0.93, I(2) = 38%; SerSer/ProSer vs. ProPro, OR = 1.04, 95% CI = 0.92-1.17, P = 0.55, I(2) = 6%; SerSer vs. ProPro/ProSer, OR = 0.98, 95% CI = 0.75-1.28, P = 0.87, I(2) = 39%). This meta-analysis suggests that the NQO1 rs1800566 polymorphism is not associated with a risk of bladder cancer. Further studies with larger samples are needed, especially for studies in Asians and Africans.