1. Department of Retroperitoneal Tumor and Anorectal Surgery, Peking University International Hospital, Beijing 102206, P.R. China
2. Department of Gastroenterological Surgery, Peking University International Hospital, Beijing 102206, P.R. China
3. Department of Gastroenterological Surgery, Laboratory of Surgical Oncology, Beijing Key Laboratory of Colorectal Cancer Diagnosis and Treatment Peking University People's Hospital, Beijing 100044, P.R. China