1. Department of Gastroenterology and Oncology, Institute of Biomedical Sciences, Tokushima University Graduate School of Medicine, Tokushima 770-8504, Japan
2. Department of Gastroenterology and Neurology, Kagawa University Graduate School of Medicine, Kagawa 761-0701, Japan
3. Department of Community Medicine for Gastroenterology and Oncology, Institute of Biomedical Sciences, Tokushima University Graduate School of Medicine, Tokushima 770-8503, Japan