[1] Dana Farber Canc Inst, Qual Control Ctr, Boston, MA 02115 USA
[2] Dana Farber Canc Inst, Dept Pediat Oncol, Boston, MA 02115 USA
[3] Dana Farber Canc Inst, Dept Biostat Sci, Boston, MA 02115 USA
[4] Massachusetts Gen Hosp, Dept Pediat, Boston, MA 02114 USA
[5] Childrens Hosp, Div Hematol Oncol, Boston, MA 02115 USA
[6] Harvard Univ, Sch Med, Dept Pediat, Boston, MA 02115 USA