1. Department of Gastrointestinal Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong 250021, P.R. China
2. Department of Gastrointestinal Surgery, Weihai Municipal Hospital, Binzhou Medical University, Weihai, Shandong 264200, P.R. China
3. Department of Pathology, Weihai Municipal Hospital, Binzhou Medical University, Weihai, Shandong 264200, P.R. China
4. Department of Gynecology, Weihai Municipal Hospital, Binzhou Medical University, Weihai, Shandong 264200, P.R. China