Duodenal gastric ulcer may cause stomach cancer. Duodenal gastric ulcer is a kind of disease mainly caused by the self-digestion of the submucosal tissues by digestive juice after the mucosa is damaged, which belongs to peptic ulcer, and the main symptoms are epigastric pain, nausea, vomiting, black stool and so on. The probability of cancerous duodenal gastric ulcer is low, but it is not excluded to cause gastric cancer. When patients find this disease, they should consult the doctor in time to find out whether there is Helicobacter pylori infection, and if there is a need to carry out quadruple bactericidal treatment, and pay attention to the rechecking of breath test and gastroscopy after the treatment, so as to find out the bactericidal situation and the ulcer situation. The occurrence of gastric cancer is related to many factors, including H. pylori infection, precancerous lesions, hereditary factors, environmental factors, etc. It is recommended to have regular gastroscopy to clarify whether there are lesions and timely treatment.