1. Department of Surgery, Hebei Medical University, Shijiazhuang, China.
2. Department of Surgery and Oncology, Hebei General Hospital, Shijiazhuang, China.
3. Department of General Surgery III, Baoding First Central Hospital, Baoding, China.
4. Department of Epidemiology and Statistics, School of Public Health, Guilin Medical University, Guilin, China.
5. Department of Pathology, Baoding First Central Hospital, Baoding, China.