1. Department of Cancer Epidemiology; National Cancer Center/Cancer Hospital; Chinese Academy of Medical Sciences & Peking Union Medical College; Beijing China
2. Department of Epidemiology; Cancer Institute/Hospital of Cixian; Cixian China
3. Department of Epidemiology; Cancer Institute/Hospital of Linzhou; Linzhou China
4. Department of Endoscopy; Cancer Institute/Hospital of Linzhou; Linzhou China
5. Department of Pathology; National Cancer Center/Cancer Hospital; Chinese Academy of Medical Sciences & Peking Union Medical College; Beijing China
6. National Office for Cancer Prevention and Control; National Cancer Center/Cancer Hospital; Chinese Academy of Medical Sciences & Peking Union Medical College; Beijing China