[1] Hosp Sick Children, Div Hematol Oncol, Toronto, ON M5G 1X8, Canada
[2] Univ Toronto, Dept Pediat, Toronto, ON, Canada
[3] Univ Toronto, Dept Hlth Policy Management & Evaluat, Toronto, ON, Canada
[4] Univ Toronto, Dept Publ Hlth Sci, Toronto, ON, Canada
[5] Natl Canc Inst, Pediat Oncol Branch, Rockville, MD USA
[6] Childrens Hosp Philadelphia, Div Oncol, Philadelphia, PA 19104 USA
[7] Univ Texas, SW Med Ctr, Dept Pediat, Dallas, TX 75230 USA