1. Department of Gastroenterology, Provincial Hospital Affiliated to Shandong University, Jinan 266042, Shandong, China
2. Department of Gastroenterology, The Affiliated Qingdao Central Hospital of Qingdao University, Qingdao 266000, Shandong, China
3. Department of Oncology, The Affiliated Qingdao Central Hospital of Qingdao University, Qingdao 266000, Shandong, China