As shown in Table 2, the null genotype of GSTM1 was associated with an elevated risk of gastric cancer in the HP positive sub-group (OR=1.928, 95% CI: 1.028-3.615, Pheterogeneity=0.065), while no significant association was found in the HP negative sub-group (OR=0.969, 95% CI: 0.618-1.521, Pheterogeneity=0.168). This evidence concerns the gene GSTM1 and gastric cancer.