Follow-up: History and physical examination every 3-6 months for 2 years, then every 6 months for a total of 5 years; monitoring of CEA every 3-6 months for 2 years, then every 6 months for a total of 5 years; CT of the abdomen and pelvis once a year for 3 years; colonoscopy within 1 year after surgery and as needed thereafter. Management of elevated CEA levels: CEA levels generally decrease gradually to normal levels in patients after obtaining radical resection. Management of elevated postoperative CEA levels includes colonoscopy, CT scans of the chest, abdomen, and pelvis, and physical examinations, with consideration of PET-CT. For elevated CEA levels with normal imaging findings, repeat CT scans are recommended once every 3 months until the lesion is found or the CEA level stabilizes or decreases. In this group of patients, PET-CT may be considered if the risk of recurrence is considered.