1. Pediatric Hematology/Oncology, Department of Pediatrics University Hospital Tuebingen Tuebingen Germany
2. German Childhood Cancer Registry, Division of Childhood Cancer Epidemiology, Institute for Medical Biostatistics, Epidemiology, and Informatics University Medical Center Mainz Mainz Germany
3. Pediatric and Adolescent Medicine University Medical Center Augsburg Germany
4. Pediatric Oncology Department Otto von Guericke University Children's Hospital Magdeburg Germany
5. Clinic of Pediatrics, Klinikum Dortmund Witten/Herdecke University Witten Germany