[1] Karolinska Inst, Dept Surg Gastroenterol K53, CLINTEC K53, SE-14186 Stockholm, Sweden
[2] Karolinska Univ Hosp, Dept Surg Gastroenterol, Stockholm, Sweden
[3] DKFZ Heidelberg, Heidelberg, Germany
[4] Univ Heidelberg, Dept Med 2, Mannheim Med Fac, D-6800 Mannheim, Germany
[5] Univ Heidelberg, Inst Pathol, Mannheim Med Fac, D-6800 Mannheim, Germany
[6] Univ Regensburg, Dept Microbiol, Regensburg, Germany
[7] Univ Kiel, Dept Pathol, D-2300 Kiel, Germany
[8] Univ Belgrade, Dept Med, Belgrade, Serbia
[9] New York Med Ctr, Dept Epidemiol, Valhalla, NY USA
[10] European Inst Oncol, Div Epidemiol & Biostat, Milan, Italy