[1] Univ Roma La Sapienza, Div Gastroenterol, Dept Clin Med, I-00137 Rome, Italy
[2] Ist Studio Prevenz Oncol, Tuscany Canc Registry, Florence, Italy
[3] Univ Ferrara, Ferrara Canc Registry, I-44100 Ferrara, Italy
[4] Ist Super Sanita, Canc Epidemiol Unit, Natl Ctr Epidemiol Surveillance & Hlth Promot, I-00161 Rome, Italy