Gastrointestinal malignant tumors can cause symptoms such as difficulty in swallowing, loss of appetite, indigestion, vomiting blood, abdominal pain, diarrhea and black stool. Gastrointestinal malignant tumors mainly include esophageal cancer, stomach cancer, pancreatic cancer, liver cancer, intestinal cancer, etc. The symptoms caused by tumors in different parts are different. Esophageal cancer will cause relative narrowing of the esophageal tube, so patients will have difficulty in swallowing, sternal burning and pain as the main manifestations. Gastric cancer will affect the function of stomach, so that the food cannot be digested and emptied better, so the patient will suffer from loss of appetite and indigestion. In the advanced stage, patients may also vomit blood because of the damage caused by the cancerous tissue to the stomach lining. When pancreatic cancer attacks, patients will experience severe abdominal pain, accompanied by indigestion and other symptoms. Liver cancer may cause pain in the lower abdomen, jaundice, and ascites in the advanced stage. Bowel cancer will affect the digestive and absorption functions of the intestines, and patients will suffer from abdominal pain, bloating, diarrhea and other symptoms. Bleeding caused by digestive tract tumor will lead to dark color of stool after oxidation of digestive fluid, and patients will have tarry stool.