There is no certain relationship between diarrhea and stomach cancer. Many conditions can lead to diarrhea, such as acute gastroenteritis, gastrointestinal cold and so on. Stomach cancer is a cancerous transformation of stomach, the tumor affects the normal digestion and absorption function of stomach, causing indigestion, which may also lead to diarrhea, but diarrhea and stomach cancer are not connected. Some chronic inflammation of pancreas or other lesions of liver may cause indigestion, especially after eating greasy food, which will cause diarrhea. In the early stage of stomach cancer, there may be fullness and discomfort in the upper abdomen, especially after eating, and there may be acid reflux, belching and other symptoms. However, diarrhea is not necessarily a symptom of stomach cancer, and diarrhea does not mean that there is stomach cancer.