There is not much blood in the stool of colon cancer. According to the location of tumor occurrence, some are in the right half colon, some are in transverse colon, some are in the left half colon, and the performance of colon tumor is different in different parts. The right half of the colon is thicker, and the progress of colon tumor is bigger before the patient can find it, or the tumor may have grown to the outside of the intestinal wall and invaded the organs in the abdominal cavity, because the colon tumor is bigger, so the surface may be ulcerated and bleed, but the amount of bleed is smaller, and the patient’s performance is the most black stools, and it may also be manifested as the symptom of anemia, which means that dizziness is often seen. If the transverse colon or the left half of the colon has a tumor, most of the performance is infiltrative growth, easy to cause intestinal incomplete obstruction or complete obstruction, resulting in relatively little bleeding from the colon.