1. Department of Pediatric Hematology and Oncology, Hannover Medical School, Hannover, Germany;
2. Pediatric Hematology and Oncology, Pediatrics III, Essen University Hospital, Essen, Germany;
3. Department of Pediatrics, St. Anna Children's Hospital/Children's Cancer Research Institute, Medical University of Vienna, Vienna, Austria;
4. Dutch Childhood Oncology Group, The Hague, The Netherlands;
5. Department of Pediatrics, Aarhus University Hospital, Skejby, Denmark; and
6. Department of Pediatric Oncology/Hematology, Erasmus Medical Center/Sophia Children’s Hospital, Rotterdam, The Netherlands