Affiliation: | 1. Department of Paediatrics, Aarhus University Hospital Skejby, , Aarhus, Denmark;2. Department of Paediatrics, Oslo University Hospital, Rikshospitalet, , Oslo, Norway;3. Children's Hospital, Helsinki University Central Hospital, , Helsinki, Finland;4. Department of Paediatric Oncology, The Queen Silvia Children's Hospital, , Gothenburg, Sweden;5. Department of Paediatrics, Landspitalinn University Hospital, , Reykjavik, Iceland;6. Department of Paediatric Oncology, Karolinska University Hospital, , Stockholm, Sweden;7. Department of Paediatrics and Adolescent Medicine, University Hospital Rigshospitalet, , Copenhagen, Denmark |