Patients who have undergone apparently curative resection for colorectal cancer are followed up for four reasons:

1. to detect metastatic disease in the hope that early detection and treatment will result in improved survival;
2. to survey the remaining colon and rectum to detect intraluminal recurrence and/or other cancer or adenomatous polyps;
3. for the psychological support of the patient;
4. for audit purposes.

In this guideline, only the first two reasons are addressed.

Individual randomised trials show no advantage of follow up^{238, 239, 240, 241, 242} as measured by survival. Meta-analyses indicate that follow up can offer survival benefit by means of earlier detection of metastatic disease. In particular, interval CT scanning and serial carcinoembryonic antigen (CEA) levels appear to be useful in this respect.^{243, 244, 245} Evidence level 1++,1+

There is no evidence that FOBT is of any value in follow up of patients after curative resective surgery.

There is some conflicting evidence that those who have had curative resection of rectal cancer may benefit from endoscopic surveillance.^{242, 246} As the incidence of colorectal cancer is increased after the first occurrence, and adenomatous polyps occur with increased frequency,³⁵ most clinicians would recommend colonoscopic follow up in patients after colorectal cancer resection as for those with adenomatous polyps (see section 2.7.3).

Patients who have undergone curative resection for colorectal cancer should undergo formal follow up in order to facilitate the early detection of metastatic disease.

Interval CT scanning and CEA estimation may be of value in the follow up of patients who have undergone curative resection for colorectal cancer but further studies are required to define an optimum approach.

Colonoscopic follow up after curative resection for colorectal cancer should be carried out as for adenomatous polyps.

Where the clinician suspects intraluminal recurrence, colonoscopy is indicated.

Clinicians should be aware of the need to have symptoms and signs of metastatic recurrence promptly investigated.