[1] Oulu Univ Hosp, Dept Pediat, Oulu, Finland
[2] Univ Oulu, Res Unit Clin Med, Oulu, Finland
[3] Uppsala Univ Hosp, Dept Pediat Oncol & Hematol, Uppsala, Sweden
[4] Uppsala Univ, Dept Womens & Childrens Hlth, Uppsala, Sweden
[5] Univ Hosp Rigshospitalet, Dept Pediat & Adolescence Med, Clin Pediat Oncol & Hematol, Copenhagen, Denmark
[6] Umea Univ Hosp, Dept Pediat Hematol & Oncol, Umea, Sweden
[7] Turku Univ Hosp, Dept Pediat, Turku, Finland
[8] Univ Helsinki, Childrens Hosp, Dept Hematol Oncol & Stem Cell Transplantat, Helsinki, Finland
[9] Oulu Univ Hosp, Dept Surg, Oulu, Finland
[10] Uppsala Univ Hosp, Dept Diagnost Radiol, Uppsala, Sweden
[11] Oulu Univ Hosp, Res Serv Unit, Oulu, Finland
[12] Kuopio Univ Hosp, Dept Pediat, Kuopio, Finland
[13] Tampere Univ, Univ Hosp, Ctr Child Hlth Res, Tampere, Finland
[14] Karolinska Univ Hosp, Astrid Lindgren Childrens Hosp, Stockholm, Sweden
[15] Karolinska Inst, Dept Womens & Childrens Hlth, Stockholm, Sweden
[16] Lund Univ, Skane Univ Hosp, Dept Pediat Oncol, Lund, Sweden
[17] Linkoping Univ Hosp, Dept Pediat, S-58185 Linkoping, Sweden