1 State Key Laboratory of Cancer Biology, National Clinical Research Center for Digestive Diseases, Xijing Hospital of Digestive Diseases, Air Force Medical University, Xi'an, Shaanxi 710032, China.
2 Department of Gastroenterology, Honghui Hospital, Xi'an, Shaanxi 710054, China.
3 Department of Gastroenterology, Xianyang Center Hospital, Xianyang, Shaanxi 712099, China.