1. Department of Pediatric Hematology and Oncology; University Medical Center Utrecht; Wilhelmina Children's Hospital Utrecht The Netherlands
2. Princes Maxima Center for Pediatric Oncology; Utrecht; The Netherlands
3. Department of Pediatric Hematology and Oncology; Erasmus MC; Sophia Children's Hospital Rotterdam The Netherlands
4. Department of Pediatric Oncology; Emma Children's Hospital; Academic Medical Centre Amsterdam The Netherlands
5. Department of Statistics; Dutch Cancer Institute (NKI-AvL); Amsterdam The Netherlands
6. Department of Pathology; Cardiff University School of Medicine; Heath Park Cardiff United Kingdom
7. Institute of Child Health; University College London; London United Kingdom
8. Alder Hey Children's NHS Foundation Trust; Liverpool; United Kingdom
9. Saarland University; Department of Pediatric Oncology & Hematology; Homburg Germany
10. Institut d'Hématologie et d'Oncologie Pédiatrie; Lyon; France
11. Department of Pediatric Oncology; Hospital Materno-Infantil; Malaga Spain
12. Pediatric Oncology Unit; Department of Hematology and Pediatric Oncology; Fondazione IRCCS Istituto Nazionale dei Tumori; Milan Italy