1. Department of Pathology; The Netherlands Cancer Institute-Antoni van Leeuwenhoek; Amsterdam The Netherlands
2. Department of Pathology; National University Hospital; Reykjavik Iceland
3. Faculty of Medicine; University of Iceland; Reykjavik Iceland
4. Icelandic Cancer Registry, Icelandic Cancer Society; Reykjavik Iceland
5. Department of Pathology; VU University Medical Center; Amsterdam The Netherlands
6. Department of Surgery; National University Hospital; Iceland
7. Department of Gastroenterology; National University Hospital; Iceland