Xu-Feng Zhang1, Timothy M Pawlik2. 1. Department of Hepatobiliary and Pancreatic Surgery and Institute of Advanced Surgical Technology and Engineering, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China. 2. Department of Surgery, The Urban Meyer III and Shelley Meyer Chair for Cancer Research, The Ohio State University Wexner Medical Center and James Comprehensive Cancer Center, Columbus, OH, USA. tim.pawlik@osumc.edu.