[1] Univ Latvia, Inst Clin & Prevent Med, Fac Med, 19 Raina Blvd, LV-1006 Riga, Latvia
[2] Riga East Univ Hosp, Riga, Latvia
[3] Vanderbilt Univ, Dept Med, Sch Med, Div Gastroenterol, Nashville, TN 37232 USA
[4] Digest Dis Ctr GASTRO, Riga, Latvia
[5] Reg Oncol Ctr, Semey, Kazakhstan
[6] Reg Diagnost Ctr, Alma Ata, Kazakhstan
[7] Cent Asian Canc Inst, Astana, Kazakhstan