1. The First Clinical Medical College, Lanzhou University, Lanzhou, Gansu, China, 730030
2. Department of Gastric Surgery, Gansu Wuwei Tumour Hospital, Wuwei, Gansu, China, 733000
3. Department of General Surgery, The First Hospital of Lanzhou University, Lanzhou, Gansu, China, 730030
4. Department of Anesthesiology, The First Hospital of Lanzhou University, Lanzhou, Gansu, China, 730030
5. Department of Gastroenterology, Gansu Wuwei Tumour Hospital, Wuwei, Gansu, China, 733000
6. Clinical Research Center, The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen, Guangdong, China, 518107