GSTM1 and urinary bladder cancer: Smokers with GSTM1 null genotype were at five-fold higher risk of developing bladder cancer (OR=5.0; 95% CI=1.55-16.16) while the risk was even higher with twenty-fold with NAT2 low acetylator phenotype (OR=20.5; 95% CI=2.33-80.86).