1. Department Musculo-Skeletal Tumor Service/Oncology, Haukeland University Hospital, Bergen, Norway;
2. Department Orthopedics/Oncology Service, Karolinska Hospital, Stockholm, Sweden;
3. Department Orthopedics, Lund University, Skåne University Hospital, Lund, Sweden;
4. Department Oncology, Oslo University Hospital, Norwegian Radium Hospital, Oslo, Norway;
5. Department Orthopedics, Sahlgrenska Hospital, Gothenburg, Sweden;
6. Department Orthopedics, Norrland University Hospital, Umeå, Sweden;
7. Department Oncology, Helsinki University Hospital, Helsinki, Finland;
8. Department Orthopedics, Tampere University Hospital, Tammerfors, Finland;
9. Department Orthopedics, Linköping University Hospital, Linköping, Sweden;
10. Department Orthopedics, Landspitalin, Reykjavik, Iceland;
11. Department Oncology, Lund University Hospital, Lund, Sweden;
12. Department Plastic Surgery, Helsinki University Hospital, Helsinki, Finland;
13. Department Oncology, Linköping University Hospital, Linköping, Sweden;
14. Department Orthopedics, Oslo University Hospital, Norwegian Radium Hospital, Oslo, Norway;
15. Department Oncology, Landspitalin, Reykjavik, Iceland;
16. Department Oncology, Tampere University Hospital, Tammerfors, Finland;
17. Department Pathology, Oslo University Hospital, Norwegian Radium Hospital, Oslo, Norway;
18. Department Radiology, Akademiska Sjukhuset, Uppsala, and Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden;
19. Department Centre for Clinical Research, Haukeland University Hospital, Bergen, Norway;
20. Department Department of Global Public Health and Primary Care, University of Bergen, Norway;
21. Department Cancer Epidemiology, Lund University Hospital, Lund, Sweden.