Statements & Guidelines

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Post-Polypectomy Surveillance Guidelines
HR Schneider

The adenomatous polyp is the most frequent neoplasm found during colorectal screening. Polyp removal has been shown to reduce the risk of colorectal cancer. Following diagnosis of a polyp, patients are entered into a surveillance programme of periodic colonoscopies, to discover missed synchronous polyps (6-10%), and to detect new adenomas and cancers. It has previously been shown that slower withdrawal of the colonoscope after reaching the caecum does result in a higher polyp detection rate.(1) The challenge to gastroenterologists is to screen all subjects ‘at risk”, to identify those with polyps and to conduct effective surveillance. Colonoscopy remains the gold standard investigation, but needs to be done efficiently, thoroughly and at the recommended intervals. Reducing the frequency of examinations will hopefully allow more scarce health resource to be channelled into screening programmes.
Post-polypectomy surveillance now makes up a large proportion of endoscopy practice. There is concern that endoscopists are not following published guidelines and are performing colonoscopies too frequently. The American Gastroenterology Association has recently published guidelines, which will be reviewed in this article. (2)

Surveillance Recommendations.

1. Patients with small hyperplastic polyps should be considered to have normal colonoscopies, and therefore the interval before the subsequent colonoscopy should be in 10 years; an exception is patients with hyperplastic polyp syndrome; they are at increased risk for adenomas and colorectal cancer and need to be identified for more intensive follow-up evaluation. (See below)



2. Patients with only 1 or 2 small (<1cm) tubular adenomas with only low-grade dysplasia should have their next colonoscopy in 5-10 years; the precise timing within this interval should be based on other clinical factors (such as prior colonoscopy findings, family history, and the preferences of the patient and judgement of the physician).



3. Patients with 3 to 10 adenomas, or any adenoma 1cm or greater in size, or any adenoma with villous features, or high grade dysplasia should have their next colonoscopy in 3 years, providing that piecemeal removal of the polyp has not been performed, and that the polyp(s) have been completely removed. If the follow-up colonoscopy is normal or shows only 1 or 2 small tubular adenomas with low-grade dysplasia, then the interval before the next examination should be 5 years.



4. Patients who have more than 10 adenomas at one examination should be examined at shorter (<3 years) intervals, established by clinical judgement, and the clinician should consider the possibility of an underlying familial polyposis syndrome.



5. Patients with sessile adenomas that are removed piecemeal should be considered for follow-up at short intervals (2-6 months) to verify complete removal; once complete removal has been verified, subsequent surveillance needs to be individualized based on the endoscopists judgement; completeness of removal should be based on both endoscopic and pathological assessments.



6. More intensive surveillance is indicated when the family history may indicate Hereditary Non-Polyposis Colorectal Cancer (HNPCC).

It is clear from the above that the baseline colonoscopy determines subsequent examination intervals, and is an important predictor for neoplasia. The baseline colonoscopy needs to be of high quality, and the following criteria met: the caecum must be reached, minimal colonic residue present and a minimum withdrawal time of 6-10 minutes.Slower colonoscope withdrawal has been shown to increase polyp detection rate. Hyperplastic polyps should be biopsied at baseline colonoscopy as some may be serrated adenomas, which has been linked to microsatellite instability adenocarcinoma.
Burt and Jass described the hyperplastic polyposis syndrome in 2000. (3) It consists of at least 5 histologically diagnosed hyperplastic polyps proximal to the sigmoid colon, 2 of which are greater than 1cm in diameter, or any number of hyperplastic polyps with a first degree relative with hyperplastic polyposis, or more than 30 hyperplastic polyps of any size distributed throughout the colon. These patients have a higher incidence of colorectal cancer.
Meticulous cleaning is essential to perform a thorough examination, and this requires both an effective cleaning agent and patient adherence to the preparation instructions. Bowel preparation tends to be poorer in the elderly and those who suffer constipation. Bowel prep is generally better in patients undergoing morning rather than afternoon colonoscopy.
At this stage alternative screening technologies such as CT colonography, chromoendoscopy, narrow-band imaging and magnification endoscopy are being evaluated but are not recommended as part of routine post-polypectomy surveillance. Guidelines are dynamic, based on best available evidence, and will be updated from time to time as new data becomes available. We need to stay abreast of the current guidelines to practice effectively.

References

1. Barclay RL, Vicari JJ, Doughty AS et al. Colonoscopic withdrawal times and adenoma detection during screening colonoscopy. NEJM 355; 2533-2541
2. Winawer SJ, Zauber AG, Fletcher RH et al. Gastroenterol 2006;130:1872-85
3. Burt R, Jass JR. Hyperplastic Polyposis. In: Hamilton SR, Aaltonen LA eds. Pathology and Genetics of tumours of the digestive system. Lyon: IARC Press 2000;135-6