1. From the Dana-Farber Cancer InstituteDepartment of Pediatrics and Department of Biostatistics, Harvard Medical School, and Children’s Hospital, Boston, MA; Division of Biology, California Institute of Technology, Pasadena, CA; National Wilms Tumor Study Group and Department of Biostatistics, University of Washington, Seattle, WA; and Department of Pediatrics, Roswell Park Cancer Institute, and School of Medicine and Biomedical Services, Buffalo, NY.