1. Department of General-, Visceral- and Tumor-Surgery, University of Aachen, Aachen, Germany.
2. Department of General, Visceral Surgery, and Surgical Oncology, University of Cologne, Cologne, Germany.
3. Department of General, Visceral, and Transplant Surgery, University of Mainz, Mainz, Germany.
4. Department of Visceral and Transplant Surgery, University Hospital of Zürich, Zürich, Switzerland.