1. Department of General Surgery, 306 Hospital of PLA, Beijing 100101, China
2. Department of General Surgery, 306 Hospital of PLA-Peking University Teaching Hospital, Beijing 100101, China
3. Department of General Surgery, PLA 306 Clinical Hospital of Anhui Medical University, Beijing 230000, China
4. Department of Pathology, 306 Hospital of PLA, Beijing 100101, China