1. Liver Cancer Institute, Zhongshan Hospital, and Key Laboratory of Carcinogenesis and Cancer Invasion (Ministry of Education), Fudan University, Shanghai, P. R. China
2. School of Mathematical Sciences and Center for Statistical Science, Peking University, Beijing, P. R. China
3. Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shangai, P. R. China
4. Institute of Biomedical Sciences, Fudan University, Shanghai, P. R. China
5. Cancer Research Institute, Xiangya School of Medicine, Central South University, Hunan, P. R. China
6. Division of Surgical Oncology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA