1. Department of Gastrointestinal Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
2. Cancer Foundation of China, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, P.R. China
3. Medical Research Center, Su Bei People's Hospital of Jiangsu Province, Yangzhou University, Yangzhou, Jiangsu 225001, P.R. China