1. Department of Pediatric Oncology; Dana-Farber Cancer Institute and Boston Children's Hospital, Harvard Medical School; Boston Massachusetts
2. Department of Oncology; Benjamin Bloom National Children's Hospital; San Salvador El Salvador
3. National Pediatric Oncology Unit; Francisco Marroquin Medical School; Guatemala City Guatemala
4. St. Jude Children's Research Hospital; Memphis Tennessee
5. Department of Epidemiology and Pediatrics (Division of Oncology); Columbia University; New York New York