[1] St Jude Childrens Res Hosp, Dept Epidemiol & Canc Control, Memphis, TN 38105 USA
[2] Riley Childrens Hosp, Dept Hematol Oncol, Indianapolis, IN USA
[3] Georgetown Lombardi Comprehens Canc Ctr, Canc Prevent & Control Program, Washington, DC USA
[4] Univ Toronto, Hosp Sick Children, Div Hematol Oncol, Toronto, ON, Canada
[5] Duke Univ, Dept Med, Durham, NC USA
[6] Washington Univ, Sch Med, Dept Pediat, St Louis, MO USA
[7] Fred Hutchinson Canc Ctr, Canc Prevent & Clin Stat Program, Seattle, WA USA
[8] Univ Texas MD Anderson Canc Ctr, Radiat Phys Dept, Houston, TX USA
[9] St Jude Childrens Res Hosp, Dept Oncol, Memphis, TN USA