1Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA.
2Peter O'Donnell Jr. School of Public Health, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
3Department of Epidemiology, Fay W Boozman College of Public Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA.
4Winthrop P. Rockefeller Cancer Institute, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA.
5Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
6Chiles Center, College of Public Health, University of South Florida, Tampa, Florida, USA.
7Department of Pediatrics, Stanford University, Stanford, California, USA.
8Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA.
9Aflac Cancer and Blood Disorders Center at Children's Healthcare of Atlanta, Atlanta, Georgia, USA.