Endoscopic Submucosal Dissection Versus Endoscopic Mucosal Resection for Sessile Polyps and Laterally Spreading Lesions of the Rectum - a Prospective Randomised Trial

EMR is a very effective procedure for lesions smaller than 20 mm. With this size the polyp can be removed en bloc. En bloc resection is preferred as it minimises the likelihood of residual adenoma and enhances histological assessment. It is also curative in superficially invasive submucosal disease. It eliminates the need for surgery in these patients. With lesions larger than 20 mm, the lesion is removed piece meal, often in more than 5 pieces. Care is taken to ensure that no adenoma is left behind at the point of overlap between snare resections. However, for every additional snare resection, there is the possibility that a small amount of adenoma will be left behind at this overlap point. Overall, the literature suggests that there is approximately a 15% residual adenoma rate at repeat colonoscopy in 3 months, which requires further treatment. With en bloc resection residual adenoma rate at repeat colonoscopy in is close to 0%. This has to be balanced against the relative inexperience with performing ESD, longer procedure time and higher complication rates. A randomized trial near completion is comparing endoscopic snare resection with transanal surgical resection for rectal polyps (24). Should this trial show that en bloc resection is superior in achieving complete resection without recurrence at similar complication rates, the endoscopic treatment strategy of large colorectal adenomas should be reconsidered. Since en bloc resection is technically more challenging, this should have consequences for credentialing, referral patterns and performance of removal of large colorectal polyps in reference centers only. Thus, before en bloc resection is promoted as superior, and training has to be intensified to comply with standards of safe oncologic resection of these lesions, the efficacy and safety have to be proven in a comparative randomized trial.