Kentaro Hayashi1, Akihiko Ozaki2, Tetsuya Tanimoto3. 1. Department of Gastroenterological Surgery, Kameda Medical Center, Kamogawa, Chiba 296-8602, Japan. Electronic address: hayashi.kentaro@kameda.jp. 2. General Surgery, Minamisoma Municipal General Hospital, Minamisoma, Fukushima, Japan. 3. The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.