1 Department of Gastrointestinal Surgery, Stavanger University Hospital, Stavanger, Norway.
2 Department of Clinical Medicine, University of Bergen, Bergen, Norway.
3 Division of Surgery and Oncology, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
4 Department of Surgical Oncology, Netherlands Cancer Institute, Amsterdam, the Netherlands.