1. Department of Surgery, Yeungnam University College of Medicine, Daegu, Korea.
2. Department of Surgery, Soonchunhyang University Bucheon Hospital, Bucheon, Korea.
3. Department of Surgery, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Seoul, Korea.
4. Department of Surgery, Dong-A University College of Medicine, Busan, Korea.
5. Department of Surgery, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
6. Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
7. Department of Surgery, Chungbuk National University College of Medicine, Cheongju, Korea.
8. Department of Surgery, National Cancer Center, Goyang, Korea.
9. The Korea Central Cancer Registry, National Cancer Center, Goyang, Korea.