[1] Univ Med Ctr Hamburg Eppendorf, Dept Pediat Hematol & Oncol, Hamburg, Germany
[2] Univ Childrens Hosp Zurich, Neuro Oncol Program, Zurich, Switzerland
[3] Univ Zurich Hosp, Dept Radiat Oncol, CH-8091 Zurich, Switzerland
[4] Univ Zurich, Inst Social & Prevent Med, Biostat Unit, CH-8006 Zurich, Switzerland
[5] Univ Wurzburg, Dept Neuroradiol, Wurzburg, Germany