1. School of Public Health and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Epidemiology CB#7400, Chapel Hill, NC 27599-7400, USA. E-mail: beth_newman@unc.edu
2. Division of Clinical Sciences, National Cancer Institute, 31/3A11 MSC 2440, Center Drive, Bethesda, MD 20892, USA. E-mail: liue@nih.gov