Some early gastric cancers do not present with indigestion such as bloating, but with pain in the stomach and epigastric region, which accounts for about one-third of cases. Two types of stomach pains that can be easily confused are gastric ulcers and duodenal bulb ulcers. The primary symptom of both is vague pain or burning pain in the upper abdomen, while the pain of duodenal bulb ulcer occurs before meals or on an empty stomach, or two hours after meals, and can wake people up at night. This pain is often called “hunger pain” and “fasting pain”. Therefore, it can be relieved by relieving hunger and eating a little. Gastric ulcer belongs to “pain when full”, that is, the pain starts when eating and is not relieved until 1.5 to 2 hours after eating after partial or complete emptying. It is not difficult for doctors to differentiate and diagnose this kind of characteristic stomach pain. However, when early gastric cancer is accompanied with the above two, it is often overlooked because the ulcer pain masks the gastric cancer pain. In fact, the pain of ulcer disease is relatively regular, while the pain of gastric cancer is irregular or persistent regardless of the presence or absence of “good and evil”, although it may vary in severity within 24 hours (usually more so at night). In addition, cancer of the gastric sinus may also cause changes in duodenal function, which may lead to rhythmic pain, and the symptoms may be similar to those of ulcers. Especially, if the above symptoms are treated as gastritis or ulcer disease, the symptoms can be temporarily relieved and ignored until the disease develops and complications such as bleeding and obstruction appear, which is often late. Therefore, for those who did not have stomach pain in the past, if recurrent stomach pain suddenly appears, or the pain pattern of the original chronic stomach disease changes, such as the pain in fasting or pain after eating used to be obvious in regularity, but the regularity disappears recently, or the drugs that were effective in treatment now have poor effect. The possibility of gastric cancer should be considered and further examination should be done to confirm the diagnosis.