1. Department of Internal Medicine, Kyung Hee University School of Medicine, Seoul, Korea
2. Department of Internal Medicine, Inje University College of Medicine, Seoul, Korea
3. Department of Internal Medicine, Soonchunhyang University College of Medicine, Seoul, Korea
4. Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea
5. Department of Internal Medicine, The Catholic University of Korea College of Medicine, Seoul, Korea
6. Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
7. Department of Internal Medicine, Hanyang University School of Medicine, Seoul, Korea
8. Department of Internal Medicine, Korea University College of Medicine, Seoul, Korea
9. Department of Internal Medicine, Ewha Womans University School of Medicine, Seoul, Korea
10. Cancer Early Detection Branch, National Cancer Control Institute, National Cancer Center, Goyang, Korea