1. Department of Hepatobiliary Surgery, Air Force General Hospital of PLA, Beijing 100142, P.R. China
2. Department of Radiation Oncology, Air Force General Hospital of PLA, Beijing 100142, P.R. China
3. Institute of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing 100015, P.R. China
4. Department of General Surgery, The Second People's Hospital of Guangdong Province, Guangzhou 510515, P.R. China