1. Childhood Cancer Research Group, Danish Cancer Institute, Copenhagen, Denmark
2. Childhood Cancer Center, Skåne University Hospital, Lund, Sweden
3. Department of Clinical Sciences, Lund University, Lund, Sweden
4. University of Helsinki and Hospital for Children and Adolescents, Helsinki, Finland
5. Norwegian Cancer Registry and Department of Pediatric Medicine, Oslo University Hospital and Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
6. Department of Pediatrics, Aarhus University Hospital, Aarhus, Denmark
7. Department of Pediatrics and Adolescent Medicine, Copenhagen University Hospital, Copenhagen, Denmark
8. Department of Clinical Medicine, Faculty of Health, Aarhus University and Aarhus University Hospital, Aarhus, Denmark