Sang-Woong Lee1, Kazuhisa Uchiyama2. 1. Department of General and Gastroenterological Surgery, Osaka Medical College, Takatsuki, Japan. Electronic address: sur079@osaka-med.ac.jp. 2. Department of General and Gastroenterological Surgery, Osaka Medical College, Takatsuki, Japan. Electronic address: uchi@osaka-med.ac.jp.