Liang Zong1, Masanobu Abe2, Yasuyuki Seto3, Jiafu Ji4. 1. Department of Gastrointestinal Surgery, Graduate School of Medicine, University of Tokyo, Tokyo, Japan; Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Gastrointestinal Surgery, Peking University Cancer Hospital and Institute, Hai-Dian District, Beijing 100142, China. 2. Division for Health Service Promotion, University of Tokyo, Tokyo, Japan. 3. Department of Gastrointestinal Surgery, Graduate School of Medicine, University of Tokyo, Tokyo, Japan. 4. Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Gastrointestinal Surgery, Peking University Cancer Hospital and Institute, Hai-Dian District, Beijing 100142, China. Electronic address: jijiafu@hsc.pku.edu.cn.