1. Childhood Cancer Research Group, Danish Cancer Society Research Center, Copenhagen, Denmark
2. Department of Pediatrics, Aarhus University Hospital, Aarhus, Denmark
3. Unit of Statistics and Pharmacoepidemiology, Danish Cancer Society Research Center, Copenhagen, Denmark
4. Department of Clinical Sciences, Lund University, Pediatric Oncology and Hematology, Skåne University Hospital, Lund, Sweden
5. The Icelandic Cancer Registry, Reykjavik, Iceland
6. Faculty of Medicine, University of Iceland, Reykjavik, Iceland
7. The Finnish Cancer Registry, Helsinki, Finland
8. Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Texas, Houston, USA
9. Research Management and Administration, Danish Cancer Society Research Center, Copenhagen, Denmark