1. National Cancer Control Institute, National Cancer Center, Goyang, Korea
2. Graduate School of Cancer Science and Policy, National Cancer Center, Goyang, Korea
3. Department of Internal Medicine, Kyung Hee University Hospital at Gangdong, Kyung Hee University School of Medicine, Seoul, Korea
4. Division of Gastroenterology and Hepatology, Department of Internal Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
5. Department of Internal Medicine, Hanyang University Guri Hospital, Hanyang University College of Medicine, Guri, Korea