Gastrointestinal Cancer Center Peking University Cancer Hospital Key Laboratory of Carcinogenesis and Translational Research(Ministry of Education) Beijing 100142 China;
Department of Pathology Duke University Medical School Durham NC USA;
Department of Sonography Peking University Cancer Hospital Beijing 100142 China;
Peking University Shougang Hospital Beijing 100144 China;
Peking-Tsinghua Joint Center for Life Sciences Beijing 100871 China;