[1] Hosp Univ La Fe, Pediat Oncol Unit, Valencia, Spain
[2] Univ Calif San Francisco, Dept Pediat, San Francisco, CA 94143 USA
[3] Univ Oslo, Rikshosp, N-0027 Oslo, Norway
[4] St Anna Childrens Hosp, Childrens Canc Res Inst, A-1090 Vienna, Austria
[5] Univ Chicago, Dept Pediat, Chicago, IL 60637 USA
[6] Inst Canc Res, Surrey, England
[7] Royal Marsden Hosp, Surrey, England
[8] Univ Florida, Childrens Oncol Grp, Gainesville, FL USA