NQO1 and urinary bladder cancer: When stratified by the source of control, an increased risk of bladder cancer was also suggested for variant alleles of NQO1 Pro187Ser polymorphism in the hospital-based subgroup (homozygous model: OR = 1.46, 95% CI = 1.09–1.94; recessive model: OR = 1.32, 95% CI = 1.02–1.69; dominant model: OR = 1.28, 95% CI = 1.05–1.56, and allele comparing: OR = 1.24, 95% CI = 1.07–1.43), while no effect was observed in the population-based subgroup.