1. Department of Pediatric and Adolescent Medicine, Gemeinschaftskrankenhaus Herdecke, Gerhard-Kienle-Weg 4, 58313 Herdecke, Germany
2. University of Witten/Herdecke, Witten, Germany
3. German Childhood Cancer Registry (GCCR), The Institute of Medical Biostatistics, Epidemiology, and Informatics (IMBEI), University of Mainz, Mainz, Germany
4. Department of Pediatric Oncology and Hematology, Otto Heubner Centre of Pediatric and Adolescent Medicine, Charité-Universitätsmedizin Berlin, Berlin, Germany