[1] Capital Med Univ, Beijing Friendship Hosp, Natl Clin Res Ctr Digest Dis, Beijing 100050, Peoples R China
[2] Peking Univ, Canc Hosp & Inst, Dept Gastrointestinal Oncol, Key Lab Carcinogenesis & Translat Res,Minist Educ, Beijing 100142, Peoples R China
[3] Peking Univ, Canc Hosp & Inst, Dept Canc Epidemiol, Key Lab Carcinogenesis & Translat Res,Minist Educ, Beijing 100142, Peoples R China
[4] Capital Med Univ, Natl Ctr Childrens Hlth, Beijing Childrens Hosp, Ctr Clin Epidemiol & Evidence Based Med, South Lishi Rd, Beijing 100045, Peoples R China