1. Department of General Surgery, Affiliated Hospital of Yan’an University, Yan’an, Shaanxi 716000, China
2. Department of Glandular Vascular Surgery, Affiliated Hospital of Yan’an University, Yan’an, Shaanxi 716000, China
3. Department of Pathology, Medical College of Yan'an University, Yan’an, Shaanxi 716000, China