If the following symptoms appear suddenly, we should pay more attention to them and go to the hospital for screening as soon as possible: 1. Change of bowel habit. Early stage may have diarrhea, constipation or alternating between diarrhea and constipation. With the continuous growth of the tumor, the narrowing of the intestinal lumen will lead to progressive constipation. 2.Abdominal pain and distension discomfort As the tumor continues to grow, some patients will experience abdominal distension discomfort, often hidden pain and discomfort, and may not have gastrointestinal symptoms. Due to the lack of specificity, it is often not noticed. Blood in stool The cause of blood in stool is mainly due to friction between stool and tumor surface. With the continuous growth of tumor, necrosis, ulceration and increased secretion of the tumor, the amount of blood in stool increases and the blood is bright red, and when the blood stays in the intestine for a long time, it is dark red and mixed with feces, and sometimes there are blood clots. 4. Anemia: Tumor growth requires a large amount of blood supply. Therefore, with the gradual growth of tumor, patients may have different degrees of anemia, but not the more severe the anemia, the more advanced the patient is. However, the more severe the anemia, the more advanced the patient is. Some patients with right-sided colon cancer tend to have unexplained anemia, weakness and fatigue symptoms at first.