X Xu1, J Gu1, C Zhu2, Z Yu1, N Li1, C Wang3, B Wu4. 1. a Department of General Surgery , Jin Ling Hospital, Clinical School of Medical College of Nanjing University , Nanjing, Jiangsu , P. R. China. 2. b Department of General Surgery , Shanghai No.9 People's Hospital affiliated to Shanghai Jiaotong University , Shanghai , P. R. China. 3. c Department of Thoracic Surgery , Jin Ling Hospital, Clinical School of Medical College of Nanjing University , Nanjing, Jiangsu , P. R. China. 4. d Department of Pathology , Jin Ling Hospital, Clinical School of Medical College of Nanjing University , Nanjing, Jiangsu , P. R. China.