Overall, the pooled meta-analysis of eligible case-control studies suggested that GSTM1 null genotype was significantly associated with the risk to colorectal cancer in Asian populations (Z = 3.32, P = 0.001, OR = 1.05, 95% CI: 1.02–1.07) in a fixed-effect model (Fig. 2a). The gene discussed is GSTM1; the disease is colorectal cancer.