Retroflexion in the duodenal bulb combined with tunnel and double-clip traction: the key to successful endoscopic submucosal dissection of a malignant gastric adenoma protruding through the pylorus - Schaefer, Marion; Lambin, Thomas; Hamel, Benjamin; Gandilhon, Clémentine; Jacques, Jérémie; Rivory, Jérôme; Pioche, Mathieu (Endoscopy, 2021)