[1] Capital Med Univ, Beijing Friendship Hosp, Dept Gastroenterol, 95 Yong An Rd, Beijing 100050, Peoples R China
[2] Natl Clin Res Ctr Digest Dis, Beijing 100050, Peoples R China
[3] Beijing Digest Dis Ctr, Beijing 100050, Peoples R China
[4] Beijing Key Lab Precanc Les Digest Dis, Beijing 100050, Peoples R China