1. Childhood Cancer Research Group, Danish Cancer Society Research Center, Copenhagen, Denmark
2. Unit of Statistics and Pharmaco-epidemiology, Danish Cancer Society Research Center, Copenhagen, Denmark
3. Department of Biostatistics, University of Copenhagen, Copenhagen, Denmark
4. Department of Paediatrics and Adolescent Medicine, Copenhagen University Hospital, Copenhagen, Denmark
5. Division of Paediatric Oncology and Hematology, Skane University Hospital, Lund, Sweden
6. Department of Clinical Sciences, Lund University, Lund, Sweden
7. The Icelandic Cancer Registry, Reykjavik, Iceland
8. Faculty of Medicine, University of Iceland, Reykjavik, Iceland
9. The Finnish Cancer Registry, Helsinki, Finland
10. Dana Farber Cancer Institute, Harvard University, Boston, MA, USA
11. Department of Paediatrics and Adolescent Medicine, Aarhus University Hospital, Aarhus, Denmark
12. Department of Clinical Medicine, Faculty of Health, Aarhus University and University Hospital, Aarhus, Denmark