Association between glutathione S-transferase M1 null variant and risk of bladder cancer in Chinese Han population.

Glutathione S-transferase M1 (GSTM1) is one of the most important families of phase II isoenzymes known to detoxify a variety of electrophilic compounds and carcinogens. The GSTM1 null variant is associated with decreased enzyme activity, and it has been assumed to be associated with bladder cancer. The association between the GSTM1 null variant and bladder cancer in the Chinese Han population was unclear owing to the obvious inconsistency from published studies. To quantify the association between the GSTM1 null variant and bladder cancer in the Chinese Han population, we carried out the meta-analysis. We estimated the pooled odds ratio (OR) with its 95% confidence interval (95% CI) to assess the association. Eight studies with a total of 3,887 individuals were finally included into the meta-analysis. Overall, there was an obvious association between the GSTM1 null variant and risk of bladder cancer in the Chinese Han population (OR = 1.61, 95% CI 1.41–1.84, P < 0.001). There was no heterogeneity across those eight studies (I 2 = 0%). The cumulative meta-analyses showed a trend of more obvious association between the GSTM1 null variant and risk of bladder cancer in the Chinese Han population as data accumulated by year. There was no obvious evidence of publication bias in the meta-analysis. In conclusion, the GSTM1 null variant is significantly associated with risk of bladder cancer in the Chinese Han population.