1. Department of Pediatric Hematology‐Oncology and Stem Cell TransplantationGhent University Hospital Ghent Belgium
2. Cancer Research Institute Ghent Ghent Belgium
3. Dutch Childhood Oncology Group (DCOG) The Hague the Netherlands
4. Department of EpidemiologyUniversity Medical Center GroningenUniversity of Groningen Groningen the Netherlands
5. Department of Clinical Chemistry, Microbiology and ImmunologyGhent University Hospital Ghent Belgium
6. Department of Pediatric Hematology OncologyHôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles Brussels Belgium
7. Department of Pediatric Hematology‐OncologyPrincess Máxima Center Utrecht the Netherlands
8. Erasmus MC–Sophia Children's Hospital Rotterdam the Netherlands
9. Department of Pediatric Hematology‐OncologyRadboud University Medical Center Nijmegen the Netherlands
10. Department of PediatricsUniversity Hospital Gasthuisberg Leuven Belgium
11. Department of PediatricsUniversity Hospital Saint‐Luc Brussels Belgium
12. Department of Pediatrics, Universitair Ziekenhuis BrusselVrije Universiteit Brussel Brussels Belgium
13. Department of Pediatric Oncology, Amsterdam Medical CenterEmma Children's Hospital Amsterdam the Netherlands
14. Department of Pediatric OncologyVU University Medical Center Amsterdam the Netherlands
15. Department of Pediatric Hematology‐OncologyUniversity Medical Center Groningen, Beatrix Children's Hospital, University of Groningen Groningen the Netherlands