Duodenal ulcers are almost never cancerous. Duodenal ulcers are a common condition of the digestive system and may have complications such as gastrointestinal bleeding, perforation and obstruction. Studies have shown that the chances of duodenal ulcers becoming cancerous are close to zero. Unlike gastric ulcers, duodenal ulcers tend to occur in the duodenal bulb, where the mural cells are extremely numerous and secrete acid very rapidly, which inhibits the production of carcinogenic nitrosamine salts and has a greater inhibitory effect on the production of cancer cells. For the treatment of duodenal ulcer, it can generally be achieved by regulating the diet, reducing the undesirable stimuli, adding acid inhibitors and gastric mucosa protectants, and those who are combined with Helicobacter pylori infection also need anti-Helicobacter pylori treatment. There is no need to worry about cancerous duodenal ulcers, but they should be treated actively to avoid progression and serious complications.