1. Gastroenterology Department; Federal State Budgetary Scientific Institution “Scientific research institute of medical problems of the North”; Krasnoyarsk Russia
2. Department of Internal Medicine; Khakass State University; Abakan Russia
3. Endoscopy Department; Khakass Republican Hospital; Abakan Russia
4. Department of Medicine (DIMED); Surgical Pathology & Cytopathology Unit; University of Padua; Padua Italy
5. Veneto Cancer Registry; Padua Italy