1. Department of Paediatric Oncology Astrid Lindgren Children's Hospital Stockholm Sweden
2. Childhood Cancer Research Unit, Department of Women's and Children's Health Karolinska Institutet Stockholm Sweden
3. Childhood Cancer Research Group Danish Cancer Society Research Center Copenhagen Denmark
4. Clinical Epidemiology and Biostatistics, School of Medical Sciences Örebro University Örebro Sweden
5. Clinical Epidemiology Division Karolinska University Hospital, Karolinska Institutet Stockholm Sweden
6. Department of Epidemiology and Public Health University College London London UK
7. Department of Women's and Children's Health Uppsala University Uppsala Sweden
8. Department of Children and Adolescents Oulu University Hospital Oulu Finland
9. Finnish Institute for Statistical and Epidemiological Cancer Research, Finnish Cancer Registry Helsinki Finland
10. Dana‐Farber Cancer Institute/Boston Children's Cancer and Blood Disorders Center Harvard Medical School Boston Massachusetts USA
11. Department of Pediatrics University of Helsinki and Helsinki University Hospital Helsinki Finland
12. The Icelandic Cancer Registry, Icelandic Cancer Society Reykjavik Iceland
13. Faculty of Medicine University of Iceland Reykjavik Iceland
14. Division of Paediatric Oncology and Haematology Skåne University Hospital Lund Sweden
15. Department of Clinical Sciences Lund University Lund Sweden
16. Department of Paediatrics Aarhus University Hospital Aarhus Denmark
17. Department of Clinical Medicine, Faculty of Health Aarhus University and University Hospital Aarhus Denmark