1. Clinic for Surgery and Cancer Medicine, Department of Oncology, Oslo University Hospital, Oslo, Norway;
2. Division of Virology, Norwegian Institute of Public Health, Oslo, Norway;
3. Clinic for Diagnostics and Intervention, Department of Pathology, Oslo University Hospital, Oslo, Norway;
4. Department of Oncology, University Hospital of Northern Norway, Tromsø, Norway;
5. Department of Oncology, St Olaf's University Hospital, Trondheim, Norway;
6. Department of Oncology, Haukeland University Hospital, Bergen, Norway; and
7. Department of Hematology and Oncology, Stavanger University Hospital, Stavanger, Norway