One of the most obvious symptoms of this disease is bloody stool. When it is not serious, there may be bloodshot, but when it is serious, dark red blood will flow from the anus, which is the kind of bloody stool secretion. The problem is very serious, which is also one of the early symptoms of colorectal cancer. Patients with colorectal cancer will have symptoms of dizziness and discomfort, which is anemia. This is because there is always blood in the stool and blood loss takes a long time. Because there is a tumor in the large intestine, the intestine will be narrowed, and even ulcers and erosion will occur. This is also a symptom of colorectal cancer.