1. The Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway;
2. Department of Paediatrics, Oslo University Hospital, Oslo, Norway;
3. Department of Pathology, Oslo University Hospital, Oslo, Norway;
4. Department of Neurosurgery, Oslo University Hospital, Oslo, Norway;
5. Department of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo, Norway;
6. Department of Registration, Cancer Registry of Norway, Oslo, Norway;
7. Department of Oncology, Oslo University Hospital, Oslo, Norway