1. Chief Doctor, Department of Gastroenterology, Kanagawa Cancer Center, 2-3-2 Asahi-ku, Nakao, Yokohama 241-8515, Kanagawa, Japan
2. Department of Gastroenterology, Kanagawa Cancer Center, Yokohama, Japan
3. Department of Pathology, Kanagawa Cancer Center, Yokohama, Japan
4. Department of Gastroenterology, Yokohama City University, Yokohama, Japan