1. Department of General, Visceral and Transplantation Surgery , University Hospital Heidelberg , Heidelberg , Germany
2. Department of General , Visceral and Thoracic Surgery , Nürnberg , Germany
3. Institute of Medical Biometry (IMBI) , University of Heidelberg , Heidelberg , Germany
4. Institute of Pathology , University of Mainz , Mainz , Germany
5. The Study Center of the German Society of Surgery (SDGC) , University Hospital Heidelberg , Heidelberg , Germany
6. Department of General, Visceral and Transplantation Surgery , 27203 University Hospital Tübingen , Tübingen , Germany