1. School of medicine, Nankai University, Tianjin, 300071, China
2. Department of General Surgery, The First Medical Center, Chinese PLA General Hospital, Beijing, 100853, China
3. Department of General Surgery, the First Affiliated Hospital of Army Medical University, Chongqing, 400038, China
4. Department of Gastrointestinal Surgery, Three Gorges Hospital, Chongqing University, Chongqing, 404000, China
5. Department of Radiotherapy, The Fifth Medical Center, Chinese PLA General Hospital, Beijing, 100071, China