1. Department of Colorectal Surgery, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P. R. China
2. Department of General Surgery, The Second Affiliated Hospital of Harbin Medical University Harbin, Harbin, Heilongjiang, P. R. China
3. Department of Gastrointestinal Surgery, Shenzhen Hospital, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, Guangdong, P. R. China