1. Department of Gastrointestinal Surgery, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway;
2. Department of Pathology, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway;
3. Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway;
4. Department of Registration, Cancer Registry of Norway, Institute of Population-Based Cancer Research, Oslo, Norway