1. Department of Pediatric Hematology/Oncology; VU University Medical Center; Amsterdam The Netherlands
2. Dutch Childhood Oncology Group (DCOG); The Hague The Netherlands
3. Department of Pediatric Hematology/Oncology; Erasmus University Hospital/Sophia Children's Hospital; Rotterdam The Netherlands
4. Department of Pediatric Hematology/Oncology; Hannover Medical School; Hannover Germany