1. Department of Stomatology, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215004, P.R. China
2. Department of Pathology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215006, P.R. China
3. Department of Epidemiology, School of Public Health, Medical College of Soochow University, Suzhou, Jiangsu 215123, P.R. China
4. Department of General Surgery, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215004, P.R. China