1. Department of Hematology, Erasmus University Medical Center, Rotterdam, The Netherlands;
2. Department of Hematology, VU University Medical Center, Amsterdam, The Netherlands;
3. HOVON Data Center, Erasmus MC Cancer Institute, Clinical Trial Center, Rotterdam, The Netherlands;
4. Department of Hematology, Academic Medical Center, Amsterdam, The Netherlands;
5. Department of Hematology, University Medical Center Groningen, Groningen, The Netherlands;
6. Department of Hematology, Isala Clinics, Zwolle, The Netherlands;
7. Department of Internal Medicine, St. Antonius Hospital, Nieuwegein, The Netherlands;
8. Department of Hematology, Erasmus University Medical Center, Rotterdam, Netherlands;
9. Myeloma Unit, Division of Hematology, Azienda Ospedaliero Universitaria Città della Salute e della Scienza di Torino, University of Turin, Turin, Italy; and
10. Department of Hematology, University Medical Center Utrecht, Utrecht, The Netherlands