[1] Med Univ Gdansk, Dept Pediat Surg, Gdansk, Poland
[2] Univ Padua, Dept Pediat, Padua, Italy
[3] Insel Hosp, Dept Pediat Surg, Bern, Switzerland
[4] Great Ormond St Hosp Sick Children, Dept Pediat Oncol, London, England
[5] Inst Gustave Roussy, Dept Pediat Oncol, Paris, France
[6] AMC Univ Amsterdam, Dept Pediat Oncol, Amsterdam, Netherlands
[7] SIOPEL Trial Off, CCLG Data Ctr, Leicester, Leics, England
[8] Birmingham Childrens Hosp, Dept Pediat Oncol, Leicester, Leics, England
[9] SIOPEL Biostat Off, IBCSG Coordinating Ctr, Bern, Switzerland
[10] Univ Bern, Inst Pathol, Dept Surg Pathol, Bern, Switzerland