The gastrointestinal system is mainly responsible for the digestion and absorption of food in the body. The main symptoms of early cancer in this area include malnutrition, gastrointestinal malfunction, progressive weight loss and some symptoms after the cancer tissue invades the mucous membrane damage. In the early stage of gastrointestinal cancer, due to the influence of cancer tissues on the gastrointestinal tract, it will affect the digestion and absorption of nutrients, which will cause weight loss, fatigue and other problems in the body. In addition, the growth of cancer tissues also needs to consume a lot of nutrients in human body, and cancer tissues take in more and faster nutrients than normal human tissues, which will also aggravate the occurrence of malnutrition symptoms. During the growth of cancer tissues, it can lead to intestinal dysfunction. These symptoms can be manifested as repeated episodes of abdominal distension and abdominal pain, as well as the rapid passage of food through the gastrointestinal tract, causing diarrhea. As food cannot be well digested and absorbed by the gastrointestinal tract, the symptoms of abdominal distension will occur during the operation of food in the gastrointestinal tract. The growth of cancer tissue, in the early stage, mainly invades the mucosal tissue of the gastrointestinal tract. The mucosal tissue is destroyed and its underlying vascular tissue may also be damaged. When these small submucosal vessels are damaged, they cause a small amount of bleeding. These bleeds are sulfated by bacteria hosted in the intestinal tract during the intestinal run and black stools appear. In the early stages of the gastrointestinal tract, the symptoms are generally not specific. One cannot rely on these so-called early symptoms to make a diagnosis. The most effective tests available are still gastrointestinal endoscopy and biopsy. The earlier the examination, the better the early diagnosis of the disease.