[1] Luigi Sacco Univ Hosp, Gastroenterol Unit, Dept Clin Sci, I-20157 Milan, Italy
[2] Luigi Sacco Univ Hosp, Dept Surg 2, I-20157 Milan, Italy
[3] Luigi Sacco Univ Hosp, Chair Pathol, I-20157 Milan, Italy
[4] John Radcliffe Hosp, Gastroenterol Unit, Oxford OX3 9DU, England
[5] John Radcliffe Hosp, Dept Colorectal Surg, Oxford OX3 9DU, England
[6] John Radcliffe Hosp, Dept Cellular Pathol, Oxford OX3 9DU, England