1. Department of Surgery, Seoul National University Boramae Medical Center, Seoul, Korea.
2. Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea.
3. Department of Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.
4. Department of Surgery, Inje University Haeundae Paik Hospital, Inje University College of Medicine, Busan, Korea.
5. Department of Surgery, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.