Department of Epidemiology, Qidong Liver Cancer Institute, Qidong, China. Department of Environmental Health and Engineering, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA. Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA. Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA. Department of Epidemiology, Harvard TH Chan School of Public Health, Boston, MA, USA. Department of Medicine, Johns Hopkins School of Medicine, Baltimore, MD, USA. Department of Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, Baltimore, MD, USA. Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA.