1. Department of Gastroenterology and Oncology, Klinikum Ludwigsburg, Ludwigsburg, Germany
2. Department of Gastroenterology, Klinikum Ludwigshafen, Ludwigshafen, Germany
3. Department of Surgery, University Medical Center Mannheim, University of Heidelberg, Mannheim, Germany
4. Department of Medicine, Cologne City Hospital, Holweide, Cologne, Germany