1 The Second Clinical Medical College of Lanzhou University, Lanzhou 730000, China.
2 The Key Laboratory of the Digestive System Tumors of Gansu Province, Second Hospital of Lanzhou University, Lanzhou 730000, China.
3 The Key Laboratory of the Digestive System Tumors of Gansu Province, Second Hospital of Lanzhou University, Lanzhou 730000, China; The Department of Tumor Surgery, Second Hospital of Lanzhou University, Lanzhou 730000, China. Electronic address: chenhaodrs@163.com.