1. German Childhood Cancer Registry, Institute for Medical Biostatistics, Epidemiology and Informatics (IMBEI), University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, Germany;
2. Pediatrics 5 (Oncology, Hematology, Immunology), Klinikum Stuttgart – Olgahospital, Stuttgart, Germany;
3. Paediatric Haematology and Oncology, University Children’s Hospital Muenster, Muenster, Germany;
4. Institute for Medical Biostatistics, Epidemiology and Informatics (IMBEI), University Medical Centre Mainz, Mainz, Germany