1. Department of Gastrointestinal Surgery, Xijing Hospital, Xi'an, Shaanxi 710032, P.R. China
2. Department of General Surgery, Shanghai Fourth People's Hospital Affiliated to Tongji University of Medicine, Shanghai 200080, P.R. China
3. State Key Laboratory of Cancer Biology, Fourth Military Medical University, Xi'an, Shaanxi 710032, P.R. China