Department of Epidemiology and Prevention, Center for Clinical Sciences, National Center for Global Health and Medicine, Tokyo, Japan. Epidemiology and Prevention Group, Center for Public Health Sciences, National Cancer Center, Tokyo, Japan. Division of Molecular and Clinical Epidemiology, Aichi Cancer Center Research Institute, Nagoya, Japan. Department of Epidemiology, Nagoya University Graduate School of Medicine, Nagoya, Japan. Department of Preventive Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan. Cancer Control Center, Osaka International Cancer Institute, Osaka, Japan. Department of Social and Environmental Medicine, Osaka University Graduate School of Medicine, Osaka, Japan. Department of Public Health, Hokkaido University Graduate School of Medicine, Sapporo, Japan. Division of Epidemiology, Department of Public Health and Forensic Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan. Department of Epidemiology and Preventive Medicine, Gifu University Graduate School of Medicine, Gifu, Japan. Department of Epidemiology, Radiation Effects Research Foundation, Hiroshima, Japan. Department of Preventive Medicine, Faculty of Medicine, Saga University, Saga, Japan.