作者单位:Department of BiostatisticsSt. Jude Children's Research HospitalMemphis,Tennessee[1]Department of OncologySt. Jude Children's Research HospitalMemphis,Tennessee[2]Department of Diagnostic ImagingSt. Jude Children's Research HospitalMemphis,Tennessee[3]Department of Epidemiology and Cancer ControlSt. Jude Children's Research HospitalMemphis,Tennessee[4]