1. Department of Surgery; Hospital Center Biel; Biel/Bienne Switzerland
2. Department of Surgery; University Hospital Basel; Basel Switzerland
3. Department of Surgery; Cantonal Hospital Olten; Olten Switzerland
4. Department of Oncology/Hematology; Cantonal Hospital St. Gallen; St. Gallen Switzerland
5. University Clinic for Visceral Surgery and Medicine; Inselspital Berne; University of Berne; Berne Switzerland
6. Basel Institute for Clinical Epidemiology and Biostatistics ceb; University Hospital Basel; Basel Switzerland
7. Department of Surgery; Lindenhof Hospital; Berne Switzerland
8. Department of Pathology; University Hospital Basel; Basel Switzerland
9. Department of Pathology; University Hospital Hamburg-Eppendorf; Hamburg Germany