GSTM1 and urinary bladder cancer: In this meta-analysis, we found that the GSTM1-null genotype was associated with bladder cancer risk in the overall population, and individually in whites, Africans and Asians (overall population: OR = 1.40, 95% CI: 1.31–1.48, P<0.00001; whites: OR = 1.39, 95% CI: 1.26–1.54, P<0.00001; Africans: OR = 1.54, 95% CI: 1.16–2.05, P = 0.003; Asians: OR = 1.45, 95% CI: 1.33–1.59, P<0.00001); as well as in controls from both hospital-based and population-based studies that included both high- and low-quality studies (Fig. 2 for the overall population; Table 4).