1. Department of Gastrointestinal Surgery, University Hospital of North Norway , Tromsø, Norway
2. Institute of Clinical Medicine, Arctic University of Norway , Tromsø, Norway
3. Department of Clinical and Registry-based Research, Cancer Registry of Norway , Oslo, Norway
4. Department of Oncology, Akershus University Hospital , Lørenskog, Norway
5. Department of Hepatobiliary and Pancreatic Surgery, Oslo University Hospital Rikshospitalet , Oslo, Norway