1. Section of Hematology/Oncology, Department of Medicine, University of Chicago and University of Chicago Cancer Research Center, IL;
2. Statistical Center, Children's Oncology Group (COG), Arcadia, CA;
3. Statistical Center, Cancer and Leukemia Group B, Durham, NC;
4. Department of Medicine, Arthur G. James Cancer Hospital and Research Institute, Columbus, OH;
5. Department of Pathology, University of Chicago, IL;
6. Department of Pediatrics, Children's Hospital of Los Angeles, CA; and
7. Department of Pediatrics, University of Chicago, IL