1. 1Department of Pediatrics, Duke University School of Medicine, Durham, North Carolina.
2. 2Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, Texas.
3. 3Division of Pediatrics, The University of Texas MD Anderson Cancer Center, Houston, Texas.
4. 4Department of Pediatrics, Section of Hematology-Oncology, Baylor College of Medicine, Houston, Texas.
5. 5Institute for Clinical Research and Health Policy Studies and the Division of Hematology/Oncology, Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts.
6. 6Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas.
7. 7Department of Sarcoma Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.