A Pilot Randomized Trial of Polypectomy Techniques for 4-6 mm Colonic Polyps

Colonoscopic polypectomy is one of the most commonly performed procedures in the United States. Despite the frequency with which polypectomy is performed, there is a remarkable absence of data regarding which polypectomy techniques most effectively remove polyps and minimize complications. As a result, polypectomy practice is based on the observational experience of experts and is how it is taught by attending physicians in fellowship training programs. It is not surprising therefore, that polypectomy practice is not consistent across the U.S., particularly for polyps in the 4-6 mm range, with 19% of endoscopists using cold forceps, 21% using hot forceps, 31% using a hot snare, 15% using a cold snare, and the remainder using a combination of these techniques.

The effectiveness of colonoscopy in the prevention of colorectal cancer (CRC) depends on polypectomy; most polyps removed during colonoscopy are < 1 cm in size. Because of their greater prevalence relative to larger polyps, polyps < 1 cm are responsible for most cases of post-polypectomy bleeding (even though the absolute risk is higher with larger polyps). Perhaps more concerning, several studies of surveillance colonoscopy have reported finding CRC within a few years of a complete colonoscopy. Nearly 30% of these cancers have occurred in colonic segments where prior polypectomy was performed, suggesting that incomplete removal may be responsible for the recurrence of neoplasia; in more than half of these cases, the initial polyp removed was 1 cm or less in size. Unfortunately, these studies are limited because the precise location of the polypectomy site relative to the subsequent cancer is uncertain.

Given the prevalence of the 4-6 mm polyp, the variation in polypectomy technique among endoscopists, and the concern about interval cancers at polypectomy sites, there is a clear and significant need to determine which technique(s) are most appropriate for clinical practice in terms of having the lowest risk for recurrent neoplasia and for major adverse effects (major bleeding, perforation).

The goal of this trial is to determine the superior method for polypectomy [cold biopsy forceps (CF), cold snare (CS), or hot snare (HS)] in the removal of adenomatous colonic polyps that are 4-6 mm in maximal diameter for the subsequent risk of recurrent neoplasia at the polypectomy site. A randomized trial comparing these three polypectomy techniques for the outcome of recurrent neoplasia at the polypectomy site requires at least 700 persons per group (at least 2100 persons total). (A trial powered to compare complication rates would require a sample size that is an order of magnitude greater than this and is beyond the feasibility and scope of both pilot and definitive trials.) Further, patients would need to undergo 3- or 5-year surveillance colonoscopy, which requires a research infrastructure to ensure complete and accurate data collection. Before embarking on this large-scale trial to examine effectiveness of polypectomy techniques, we must first demonstrate feasibility of conducting such a trial and determine the time frame, sampling frame, and resources required.

The specific aim of this proposal is to conduct a pilot randomized trial to establish: