Eating lettuce after it has been spoiled generally does not lead to the occurrence of stomach cancer, and there is no need to worry too much. However, it may lead to acute gastroenteritis. Gastric cancer is a common malignant tumor of the digestive system, mostly caused by Helicobacter pylori infection and bad dietary habits. Generally, eating spoiled lettuce once in a while will not lead to stomach cancer, but just pay attention not to eat any spoiled or moldy food in the future. However, because spoiled lettuce carries bacteria, it may induce acute gastroenteritis, which can be manifested as nausea and vomiting, loss of appetite, abdominal pain and diarrhea, fever and other symptoms, and in serious cases, it can lead to dehydration and electrolyte disorders. Therefore, when there is discomfort should go to the hospital in a timely manner.