University of Bern - Childhood Cancer Research Group, University of Bern - Childhood Cancer Research Group, University of Geneva - Cansearch Research Laboratory, St. Jude Children's Research Hospital - Department of Epidemiology, University of Lausanne - Lausanne University Hospital, University of Texas at Houston - MD Anderson Cancer Center, Emory University - Aflac Cancer and Blood Disorders Center, University of Geneva - Paediatric Onco-Haematology Unit, University of Bern - Childhood Cancer Research Group, Government of the United States of America - National Cancer Institute, University of Basel - Division of Paediatric Oncology/ Haematology, St. Jude Children’s Research Hospital - Department of Epidemiology and Cancer Control, Duke University - Duke Cancer Institute and University of Bern - Childhood Cancer Research Group