J K M Fan1,2, J W Liu3, H J Kim4. 1. Department of Surgery, The University of Hong Kong-Shenzhen Hospital, Futian, Shenzhen, China. drfanj@gmail.com. 2. Department of Surgery, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China. drfanj@gmail.com. 3. Department of Surgery, The University of Hong Kong-Shenzhen Hospital, Futian, Shenzhen, China. 4. Department of Surgery, Eunpyeong St. Mary's Hospital, The Catholic University of Korea, Seoul, Korea.