1. Department of Thoracic Surgery, The Fourth Affiliated Hospital of Hebei Medical University, Shijiazhuang, Hebei 050000, P.R. China
2. Hebei Cancer Research Center, The Fourth Affiliated Hospital of Hebei Medical University, Shijiazhuang, Hebei 050000, P.R. China
3. Department of Gastrointestinal Surgery, Peking University Cancer Hospital, Beijing 100142, P.R. China
4. Second Department of Surgery, The Fourth Affiliated Hospital of Hebei Medical University, Shijiazhuang, Hebei 050000, P.R. China