1. Department of Thoracic Surgery, Affiliated Hospital of Taishan Medical University, Tai'an, Shandong 271000, P.R. China
2. Department of Thoracic Surgery, Tai'an City Central Hospital, Tai'an, Shandong 271000, P.R. China
3. Department of Digestive Medicine, Tai'an City Central Hospital, Tai'an, Shandong 271000, P.R. China
4. Department of Oncology, Affiliated Hospital of Taishan Medical University, Tai'an, Shandong 271000, P.R. China