Early stage colon cancer usually has no manifestation, and many colon cancers evolve from colon polyps or rectal polyps. In the process of tumor progression, there may be changes in stool characteristics, such as alternating constipation and diarrhea, and in the case of bleeding, some of them may appear as black or dark red blood stools. For colon cancer that is closer to the anus, relatively red stools may appear. For patients with rectal cancer, stools may appear as pus and blood stools, or even laxity, which means that after defecation, you still want to go to defecate, but when you go again, you feel a downward sensation at the anal opening, and there is no obvious stool. If you find that the stool is different from usual, you can take a stool specimen to the hospital for laboratory test, because a small amount of bleeding cannot be seen by the naked eye, but a very small amount of gastrointestinal bleeding can be detected through the test method, which is very helpful for diagnosing colon cancer. For people in general, it is recommended to go to the hospital for colonoscopy every 3-5 years over the age of 40, which is most valuable for the diagnosis of colon cancer.