1. 1Epidemiology Program, Public Health Sciences Division, Fred Hutchinson Cancer Center, Seattle, Washington.
2. 2Department of Epidemiology, University of Washington, Seattle, Washington.
3. 3Department of Medicine, University of Washington, Seattle, Washington.
4. 4Division of Gastroenterology, Veterans Affairs Puget Sound Health Care System and University of Washington, Seattle, Washington.
5. 5Research and Development, Veterans Affairs Puget Sound Health Care System, Seattle, Washington.
6. 6Biostatistics Program, Public Health Sciences Division, Fred Hutchinson Cancer Center, Seattle, Washington.
7. 7Center for Child Health, Behavior and Development, Seattle Children's Research Institute, Seattle, Washington.
8. 8Department of Pediatrics and Nutritional Sciences Program, University of Washington, Seattle, Washington.
9. 9Cancer Prevention Program, Public Health Sciences Division, Fred Hutchinson Cancer Center, Seattle, Washington.