1. Department of Gastroenterology and Metabolism, Hiroshima University, 1-2-3 Kasumi, Minami-Ku, Hiroshima 734-8551, Japan
2. Department of Endoscopy, Hiroshima University Hospital, 1-2-3 Kasumi, Minami-Ku, Hiroshima 734-8551, Japan
3. Health Service Center, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima 739-8514, Japan
4. Department of Pathology, Hiroshima University Hospital, 1-2-3 Kasumi, Minami-Ku, Hiroshima 734-8551, Japan