Patients with rectal cancer need to be followed up regularly after radical surgery. 1.History and physical examination every 3-6 months for 2 years; then every 6 months for a total of 5 years. 2.Monitoring of CEA every 3-6 months for 2 years; then every 6 months for a total of 5 years. 3.For high-risk patients, CT examination of chest, abdomen and pelvis once a year for a total of 5 years. 4. 1 year postoperative colonoscopy. If preoperative colonoscopy was not performed, repeat colonoscopy at 3-6 months postoperatively. If there is a villous tubular adenoma larger than 1 cm or adenoma with high-grade atypical hyperplasia, repeat colonoscopy after 1 year; if there is no such condition, repeat colonoscopy 3 years after surgery and 5 years after surgery.