1. Department of Gastroenterology (I), Central Hospital of Zibo, Zibo, Shandong 255036, P.R. China
2. Department of Gastroenterology (II), Central Hospital of Zibo, Zibo, Shandong 255036, P.R. China
3. Department of Oncology (I), Central Hospital of Zibo, Zibo, Shandong 255036, P.R. China