1 Pediatric Oncology and Hematology, Children's Hospital Medical Center, University Clinics, Homburg, Germany.
2 Division for Pediatric Hematology and Oncology, Hospital for Children and Adolescents, University Hospital, Goethe University Frankfurt am Main, Frankfurt, Germany.
3 Department of Pediatric Hematology and Oncology, University Children's Hospital Muenster, Muenster, Germany.
4 Department of Pediatric Oncology, Hematology and Clinical Immunology, University of Duesseldorf, Duesseldorf, Germany.
5 Pediatric Hematology/Oncology, Department of Pediatrics, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.