Most of the colon cancer patients come to the clinic with bloody stools and are found to be colon cancer after a series of tests. Colon cancer will not keep on having blood in the stool. Intermittent blood in the stool will recover after treatment and continue to have blood in the stool after a while, thinking that it is fire, but actually it is not. Tumor is an abnormal proliferation of normal tissue cells, which also releases toxins and causes systemic damage. The degree of proliferation of abnormal proliferation is faster than normal cells and requires fast blood supply, so the proliferation speed is especially fast. The colon is divided into cecum, ascending colon, transverse colon and descending colon, and there is more blood in the left half of the colon than in the right half. The right hemicolectomy is mostly characterized by anemia and systemic depletion, and blood in stool appears very late and is mixed with stool. The left half colon cancer, like sigmoid colon cancer and rectal cancer, may cause blood in stool in early stage due to dry stool and straining, plus the tumor proliferates too fast, so it is easy to be detected by examination, so bloody stool is usually the first sign of colorectal cancer detection.