1. University Medical Centre Mannheim, University of Heidelberg; Department of Surgery; Theodor-Kutzer-Ufer 1-3 Mannheim Germany 68167 Mannheim
2. Klinikum Frankfurt Hoechst; Department of Surgery; Gotenstrasse 6-8 Frankfurt am Main Germany 68150
3. University Medical Centre Mannheim, University of Heidelberg; Day Treatment Center, Interdisciplinary Tumor Center Mannheim and III Medical Clinic; Mannheim Germany 68167
4. University Hospital Heidelberg; Institute of Medical Biometry and Informatics; INF 305 Heidelberg Germany 69120
5. Institute for Quality and Efficiency in Health Care (IQWiG); Cologne Germany