Department of Epidemiology, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, China; Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine and China International Cooperation Center for Environment and Human Health, Nanjing Medical University, Nanjing, China. Department of Epidemiology and Biostatistics, School of Public Health, Peking University Health Science Center, Beijing, China. Shandong Provincial Key Laboratory of Radiation Oncology, Cancer Research Center, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China. Cancer Institute, Fudan University Shanghai Cancer Center, Shanghai, China. Department of Epidemiology, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, China. Department of Gastroenterology, the Affiliated Hospital of Yangzhou University, Yangzhou, China. Department of General Surgery, Jiangsu Cancer Hospital, Jiangsu Institute of Cancer Research, The Affiliated Cancer Hospital of Nanjing Medical University, Nanjing, China. Department of Laboratory Medicine, Clinical Medical College of Yangzhou University, Yangzhou, China. Chinese Academy of Medical Sciences, Beijing, China. Department of Gastric Cancer, Shanghai Medical College, Fudan University Shanghai Cancer Center, Shanghai, China; Department of Gastric Surgery, Fudan University Shanghai Cancer Center, Shanghai, China. Department of Epidemiology and Biostatistics, National Clinical Research Center for Cancer, Key Laboratory of Molecular Cancer Epidemiology of Tianjin, Tianjin Medical University Cancer Institute and Hospital, Tianjin Medical University, Tianjin, China. Clinical Trial Service Unit and Epidemiological Studies Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK. Cancer Institute, Fudan University Shanghai Cancer Center, Shanghai, China; Duke Cancer Institute, Duke University Medical Center, Durham, NC, USA; Department of Population Health Sciences, Duke University School of Medicine, Durham, NC, USA. Department of Epidemiology, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, China; Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine and China International Cooperation Center for Environment and Human Health, Nanjing Medical University, Nanjing, China. Electronic address: hbshen@njmu.edu.cn.