1. Division of Gastroenterology, Showa University Fujigaoka Hospital, Yokohama 227-8501, Japan
2. Department of Gastroenterology, Shizuoka General Hospital, Shizuoka 420-0881, Japan
3. Division of Gastroenterology, Iwata City Hospital, Iwata 438-0002, Japan
4. Department of Medical Oncology, School of Medicine, Sapporo Medical University, Sapporo 060-8543, Japan