1. Orthopedic Surgery, Leiden University Medical Center, Leiden;
2. Orthopedic Surgery, Radboud University Medical Center, Nijmegen;
3. Medical Oncology, Leiden University Medical Center, Leiden;
4. Clinical Epidemiology, Leiden University Medical Center, Leiden;
5. Oncology Surgery, Medical Spectrum Twente, Enschede;
6. Pathology, Leiden University Medical Center, Leiden, The Netherlands