S G Larsen1,2, F Pfeffer3,4,2, H Kørner3,5,2. 1. Department of Gastroenterological Surgery, Oslo University Hospital, N-0424 Oslo, Norway. 2. Norwegian Colorectal Cancer Group, Norway. 3. Department of Gastroenterological Surgery, Haukeland University Hospital, Bergen, Norway. 4. Department of Clinical Medicine, University of Bergen, Bergen, Norway. 5. Department of Gastrointestinal Surgery, Stavanger University Hospital, Stavanger, Norway.