This patient has completed therapy for high-risk stage III colon cancer, and postoperative surveillance should include physical examination and serum carcinoembryonic antigen measurement every 3 to 6 months, as well as CT scans of the chest and abdomen (and pelvis for patients with rectal cancer) annually for 3 to 5 years. Colonoscopy, if done preoperatively, should be performed 1 year after resection and then repeated at 3- to 5-year intervals. Because this patient was unable to undergo colonoscopy preoperatively, this procedure should be performed initially 6 months after surgery. Postoperative surveillance is done to identify patients with relapse of colorectal cancer that is potentially curable by surgery. The risks of radiation exposure and false-positive findings leading to additional tests and possibly invasive procedures must be balanced against the benefits of surveillance studies.

Routine CT scans annually for 10 years is not indicated because most colorectal cancers recur within the first 3 years after surgery, and scanning beyond 3 to 5 years is therefore not warranted.

PET scans may be useful adjuncts to evaluate equivocal abnormalities seen on CT scans; however, they are not recommended for routine surveillance following resection of colorectal cancer and should not be used for this purpose.

A 2007 Cochrane review of follow-up strategies for patients treated for nonmetastatic colorectal cancer concluded that there is an overall survival benefit by intensifying the follow-up of patients after curative surgery, but because of the wide variations in follow-up programs included in the analysis, no conclusion could be drawn about the best combination and frequency of procedures and tests to maximize benefits and minimize harms. However, the results of this review imply that some intensity of surveillance is more beneficial than observation alone.