Stool can help us detect colorectal cancer and, to some extent, tell us how healthy the intestines are. I often use a diagram of a child lying on the side of a toilet and curiously observing it in my lectures to show the importance of observing stool. If there is blood in the stool, if the stool becomes thin or irregular in shape, if there is a change in bowel habits, if there is diarrhea, and if the stool is not clean, you should seek prompt medical attention. However, because of all the symptoms of blood in stool, many colorectal cancers are easily misdiagnosed as hemorrhoids in the early stage. Decades ago, I met two unforgettable patients, both in their twenties, who had blood in the stool but always thought it was hemorrhoids, and were already in the advanced stage of rectal cancer when they came to see me. So when you have blood in your stool, it is recommended to go to the hospital for fecal occult blood and other tests in time to rule out the risk of colorectal cancer. This is because if the tumor grows in the colon near the anus and breaks down and bleeds, there will be blood in the stool. If the tumor grows in the ascending colon, although the blood cannot be seen by the naked eye, the fecal occult blood test can detect it. If the result of fecal occult blood is positive, it means that there is something wrong with the colon, so colonoscopy and other tests are needed. In addition to abnormal stools, people with frequent bloating also need to be alert, especially the elderly. If the bloating is particularly uncomfortable and suddenly worsens over a period of time, you should seek prompt medical attention. In addition, patients with intestinal obstruction also need to rule out colon cancer. Clinically, there are many patients with intestinal obstruction who are found to have colon cancer only after surgery. Since stool is so important, will constipation increase the risk of colorectal cancer? Actually, the occurrence of colorectal cancer is affected by many factors, and there is not enough evidence to show that constipation is directly related to colorectal cancer. However, I would like to remind you that you should have good bowel habits, preferably defecate at a fixed time every day, rather go to the toilet a little earlier, don’t hold back when you have the intention to defecate, and don’t let the waste stay in your body for too long.