1. Department of Gastrointestinal Cancer Translational Research Laboratory Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education) Peking University Cancer Hospital Beijing Institute for Cancer Research Beijing 100142 P. R. China
2. Department of Radiation Oncology Beijing Tiantan Hospital Capital Medical University Beijing 100070 P. R. China
3. Department of Gastrointestinal Surgery Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education) Peking University Cancer Hospital Beijing Institute for Cancer Research Beijing 100142 P. R. China