For early detection of colorectal cancer, it is best for the general population to have a colonoscopy at the age of 50, and for the high-risk group, it is recommended to have a colonoscopy at the age of 40. Overweight, irregular life, long-term constipation, living in areas with high incidence of colorectal cancer, patients with rectal polyps, patients with digestive tract tumors, patients with female reproductive system tumors, people with long-standing ulcerative colitis, and people with colorectal cancer in the immediate family are all high-risk groups. In some remote areas where colonoscopy is not available, at least one routine stool examination and anal finger examination should be done once a year, both of which are inexpensive and can be used as the initial screening for colorectal cancer. Especially the latter, since half of the patients with colorectal cancer in China belong to rectal cancer, experienced doctors can detect rectal cancer through anal finger examination. In fact, many early colorectal cancers can be detected through colonoscopy, and the five-year cure rate of stage I early bowel cancer is over 90%, and stage II is over 85%, which is a very good result. Bowel cancer examination actually does not cost much money, for example, in Shanxi region, it only costs 300 yuan for one examination. If you are worried about the pain in the middle of the examination, you can have a painless colonoscopy, and the total amount of medicine, anesthesia and examination is 600 yuan, and all these are covered by medical insurance. Other people who need to do colonoscopy 1. Patients with blood in the stool. 2.Patients with small bumps or foreign body sensation around the anus. 3.Patients with pus, feces or odor around the anus. 4.Patients with itching and wetness around the anus. 5.Patients with burning and pain on the outer edge or inside of the anus. 6.Patients with anal swelling and pain. 7.Patients with a history of hemorrhoids, perianal abscess and anal fistula. 8, Patients with hard, monotonous stools. If repeatedly positive fecal occult blood, family history of polyps or bowel cancer, and previous history of polyps or bowel cancer, regardless of age, it is recommended to have an annual colonoscopy. Overall, colonoscopy is an important way to reduce the incidence of colorectal cancer.