1. Private Practice, Ahrensburg, Germany
2. Centre for Hereditary Tumours, Ev. Krankenhaus, Bethesda, Duisburg, Germany
3. Department of Surgery, University of Düsseldorf, Düsseldorf, Germany
4. Department of General, Visceral, Vascular and Paediatric Surgery, Saarland University Hospital, Homburg, Germany
5. Surgical Department, MediClin Müritz-Klinikum, Waren, Germany