Efficacy of EndoClot Spraying After Endoscopic Resection of Large Colorectal Polyps

Description

Colorectal cancer is the second most common cause of cancer death in the United States and Europe. The effectiveness of colonoscopy in reducing the risk of dying from colorectal cancer relies on the detection and safe resection of neoplastic polyps to prevent incident cancers. Most polyps are small and can be easily removed using snare with or without electrocautery. Because the risk of prevalent cancer or transition to cancer increases with polyp size, effective and safe resection of large polyps is particularly important.

Endoscopic mucosal resection (EMR) is evolving as the primary endoscopic technique to remove large non-pedunculated polyps. These flat or sessile polyps are defined as lateral spreading tumors with a low vertical axis that extend laterally along the luminal wall. Several mostly retrospective studies from Europe, the U.S. and Japan, have demonstrated a high "cure" rate, with results lending credence to the shift from surgical resection to endoscopic management of these lesions. Of concern, however, is 1) a fairly high overall complication rate of 8-26% in prospective studies3-7, and 2) as well the persistence of residual neoplasia on follow-up endoscopy ranging from 16% to 46%3, 6, 8. The former is the main topic of the present study.

Severe complications including bleeding associated with a standard diagnostic or screening colonoscopy, which may include resection of predominantly smaller polyps, are uncommon. Significant bleeding occurs in 0.2 to 0.5% of patients (defined as a 2mg drop in Hemoglobin) 9, 10. The risk of severe complications increases with polyp size; here, again, the most common complication is bleeding reported in 2 to 24% of polyp resections. In one recent analysis the rate of delayed bleeding in colonic EMR was 7.5%1.

In addition to size, other factors may affect complications. These include type of resection (piecemeal versus en-bloc), polyp location (right colon with a thinner wall than the left colon), age and comorbidities, especially those that affect clotting abilities (e.g. renal insufficiency, liver disease, use of anticoagulation). Studies that have examined variables, which may directly decrease the risk of complications associated with large polyp resection, are limited.

It is apparent that resection of a large polyp leaves behind a large mucosal defect. The mucosal ulcer that forms after polyp resection can take several weeks to heal. Bleeding complications typically occur within 7 to 10 days, requiring often admission, a repeat colonoscopy to stop bleeding, and possible blood transfusions. The rates depend on size, and have been shown to be around 1.5%-2.6% overall. It is significantly higher in larger adenomas of 2 cm and more, namely 6.5% in another recent meta analysis.

To reduce the risk of bleeding various measures have been proposed which also have been summarized in several recent meta analyses. These include coagulation, clipping and others, but only few randomized trials are available: Coagulation not effective in a recent meta analysis14, but only 4 of the 12 studies were randomized and these included all mostly smaller polyps or polyps of all sizes or pedunculated polyps. In a recent randomized trial, clipping has been shown to reduce bleeding esp. on the right colonic side. However, clipping of larger areas is time consuming and may add to costs in several ways.

Our primary aim is to examine whether EndoClot application (a special form of longer lasting spray on the mucosal defect after EMR/ESD of large non-pedunculated colorectal polyps (20mm) will reduce the risk of delayed bleeding. We hypothesize that EndoClot application will reduce the risk of delayed bleeding by at least 3/4 (i.e. from 7.5% to 1.5%) based on an initial assumption of a 7.5% delayed bleeding rate.

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