Endoscopic resection of adenomas in the colon is the cornerstone of effective colorectal cancer prevention. Endoscopic mucosal resection (EMR) is currently the most used technique for resection of large distal colorectal adenomas, however, maintains some important limitations. In large lesions, EMR can often only be performed in a piecemeal fashion resulting in relatively low R0-resection rates and high recurrence rates. Endoscopic submucosal dissection (ESD) is a newer procedure that is more difficult resulting in a longer procedural time, but is promising due to the high en-bloc resection rates and the very low recurrence rates. The aim of this multicenter randomized study is to compare EMR and ESD with regard to recurrence rates and radical (R0) resection rates, and to put this into perspective against the costs and complication rates of both strategies and the burden perceived by patients on the long term-term.

Inclusion Criteria:

• non-pedunculated polyp larger than 20 mm in the rectum, sigmoid or descending colon found during colonoscopy
• indication for endoscopic treatment
• ≥18 years old
• Written informed consent

Exclusion Criteria:

• suspicion of malignancy, as determined by endoscopic findings (invasive Kudo pit pattern, Hiroshima type C) or proven malignancy at histology
• prior endoscopic resection attempt
• presence of synchronous distal advanced carcinoma that requires surgical resection
• the risk exceeds the benefit of endoscopic treatment, such as patient's with an extremely poor general condition or a very short life expectancy
• the inability to provide informed consent