1. Department of Gastrointestinal Surgery, Binzhou Medical University Hospital, Binzhou, Shandong 256603, P.R. China
2. Breast Treatment Center, The Second Affiliated Hospital of Shandong First Medical University, Taian, Shandong 271000, P.R. China
3. Department of Gastrointestinal Surgery, Dongying People's Hospital, Dongying, Shandong 257091, P.R. China