1. Department of Geriatric Gastroenterology, Xi'an No. 1 Hospital, Xi'an 710002, Shaanxi, China
2. Department of Oncology, Affiliated Hospital of Yan'an University, Yan'an 716000, Shaanxi, China
3. Department of General Surgery, Baoji People's Hospital, Baoji 721000, Shaanxi, China
4. Department of Gastroenterology, Affiliated Hospital of Yan'an University, Yan'an 716000, Shaanxi, China