1. Department of Pathology, Jining First People's Hospital, Jining, Shandong 272111, P.R. China
2. Department of Gastrointestinal Surgery, Jining First People's Hospital, Jining, Shandong 272111, P.R. China
3. Department of Pathology, Jining Tumor Hospital, Jining, Shandong 272000, P.R. China