1 Division of Gastroenterology and Hepatology, International University of Health and Welfare, Narita Hospital, Narita, Japan; Division of Research and Development for Minimally Invasive Treatment, Cancer Center, Keio University School of Medicine, Tokyo, Japan.
2 Department of Gastroenterology, Nippon Medical School Graduate School of Medicine, Tokyo, Japan.
3 Division of Research and Development for Minimally Invasive Treatment, Cancer Center, Keio University School of Medicine, Tokyo, Japan; Division of Gastroenterology and Hepatology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan.