Endoscopic Resection of Non-ampullary Duodenal Adenomas: Endoscopic Mucosal Resection (EMR) vs. Endoscopic Full-thickness Resection With the 'Duodenal Full-thickness Resection Device' (dFTRD)

Inclusion Criteria: * duodenal adenoma * age 18 or older * written informed consent Exclusion Criteria: * duodenal adenomas with a size \> 25 mm * duodenal adenomas with 20 mm or less distance to the major and/or minor duodenal papilla * presence of two or more duodenal adenomas * suspected or histologically confirmed malignancy * tumor disease (exception: after successful curative treatment) * conditions/diseases of the upper GI-tract that impair advancing of the devices into the duodenum * moribund patient * pregnancy and breastfeeding * patients that cannot give informed consent (e.g. psychiatric disorders, language barrier,...) * other contraindications for duodenal resections