From the Division of Pediatric Oncology (K.M.K., D.D.K., S.M.B., M.M., M.A.W.), Babies and Children's Hospital of New York, Columbia-Presbyterian Center of New York Presbyterian Hospital, New York, New York, U.S.A.; the Department of Pediatrics (K.M.K., M.A.W.) and the Division of Epidemiology (J.S.J.), Joseph L. Mailman School of Public Health and Herbert Irving Comprehensive Cancer Center, College of Physicians and Surgeons, Columbia University, New York, New York, U.S.A.