Leiden University - Department of Orthopaedic Surgery, IRCCS Istituto Ortopedico Rizzoli di Bologna - Musculoskeletal Oncology Department, Radboud University Nijmegen - Radboud University Medical Center, Leiden University - Department of Medical Statistics and Bioinformatics, Fondazione IRCCS Istituto Nazionale dei Tumori, IRCCS Istituto Ortopedico Rizzoli di Bologna - Musculoskeletal Oncology Department, University of Amsterdam - Department of Orthopaedic Surgery, University of Groningen - Department of Orthopaedics, Royal National Orthopedic Hospital, London, Leiden University - Department of Medical Oncology, Medical University of Graz, Medical University of Innsbruck - Department of Orthopedic Surgery, Kanazawa University - Graduate School of Medical Sciences, Harvard University - Massachusetts General Hospital, Peking University - Department of Orthopedic Oncology, University of Toronto - Musculoskeletal Oncology Unit, Independent and Leiden University - Department of Orthopedics