Helicobacter pylori can increase cancer risk by promoting the conversion of nitrite and nitrosamine; inflammatory process of the gastric epithelium induced by Hp infectious disease and environmental infective factors speeds up the extreme growth of mucosal epithelial cells, giving rise in disordered tumorigenesis; Helicobacter pylori toxic products CagA and VacA may have a carcinogenic effect, and the detection accuracy of anti-CagA [19]. The gene discussed is HP; the disease is infectious disease.