From the genetics perspective, it has been reported that genetic polymorphisms of some metabolic enzymes and genes such as cytochrome p450 2E1 (CYP2E1),63 glutathione S-transferase mu 1 (GSTM1),64 and glutathione S-transferase theta 1 (GSTT1)65 are closely related to the development of gastric cancer. Here, GSTM1 is linked to gastric cancer.