1. Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland, USA
2. Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA
3. Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland, USA
4. Division of Laboratory Sciences, U.S. Centers for Disease Control and Prevention, Atlanta, Georgia, USA