1 Department of General Surgery, Institute of Hepato-Biliary-Pancreas and Intestinal Disease, Affiliated Hospital of North Sichuan Medical College, Nanchong, 637000, PR China.
2 Department of General Surgery, Institute of Hepato-Biliary-Pancreas and Intestinal Disease, Affiliated Hospital of North Sichuan Medical College, Nanchong, 637000, PR China; Affiliated Hospital of North Sichuan Medical College, Nanchong, 637000, PR China. Electronic address: yixingren@nsmc.edu.cn.