[1] Aarhus Univ, Hosp Skejby, Dept Paediat, DK-8200 Aarhus, Denmark
[2] Univ Hosp, Dept Paediat, Oulu, Finland
[3] Oslo Univ Hosp, Rikshosp, Dept Paediat, Oslo, Norway
[4] Landspitalinn Univ Hosp, Dept Paediat, Reykjavik, Iceland
[5] Queen Silvia Childrens Hosp, Dept Paediat Oncol, Gothenburg, Sweden