Department of General Surgery, Lanzhou University Second Hospital, Lanzhou 730030, China; Clinical Center of Gastroenterology, Lanzhou University Second Hospital, Lanzhou 730030, China. Department of General Surgery, Lanzhou University Second Hospital, Lanzhou 730030, China. Department of General Surgery, Lanzhou University Second Hospital, Lanzhou 730030, China; Department of Hepatology, Lanzhou University Second Hospital, Lanzhou 730030, China.