[1] Univ Childrens Hosp Munster, Dep Ped Haematol Oncol, Munster, Germany
[2] Univ Hosp Munster, Dep Ped Haematol Oncol, Munster, Germany
[3] Univ Hosp Hamburg Eppendorf, Dep Ped Haematol Oncol, Hamburg, Germany
[4] Univ Med Ctr Schleswig Holstein, Dep Ped Haematol Oncol, Kiel, Germany
[5] Univ Hosp Erlangen, Dep Pediat Oncol, Erlangen, Germany