[1] Lanzhou Univ, Dept Hosp & Clin Med Sch 2, Lanzhou 730030, Peoples R China
[2] Key Lab Digest Syst Tumors Gansu Prov, Lanzhou 730030, Peoples R China
[3] Lanzhou Univ, Hosp & Clin Med Sch 2, Dept Ophthalmol, Lanzhou 730030, Peoples R China
[4] Lanzhou Univ, Hosp & Clin Med Sch 2, Dept Gen Surg, Lanzhou 730030, Peoples R China
[5] Lanzhou Univ, Hosp & Clin Med Sch 2, Dept Pneumol, Lanzhou 730030, Peoples R China