[1] Seoul Natl Univ, Coll Med, Childrens Hosp, Div Pediat Neurosurg, Seoul 110744, South Korea
[2] Seoul Natl Univ, Coll Med, Childrens Hosp, Dept Pathol, Seoul 110744, South Korea
[3] Seoul Natl Univ, Coll Med, Childrens Hosp, Dept Pediat,Canc Res Inst, Seoul 110744, South Korea
[4] Seoul Natl Univ, Coll Med, Childrens Hosp, Dept Radiat Oncol, Seoul 110744, South Korea