1. Centro Prevenzione Oncologica Regione Piemonte and Azienda Ospedaliero-Universitaria S. Giovanni Battista di Torino, Turin, Italy
2. Gastroenterology Unit, S Bonifacio Hospital, ULSS 20, Verona, Italy
3. Surgery Unit II, Istituto Europeo di Oncologia, Milan, Italy
4. Epidemiology Unit. ASL ‘Citta’ di Milano’, Milan Italy
5. Institute for Cancer Study and Prevention, Florence, Italy
6. Gastroenterology Unit, Infermi Hospital, ASL 12, Biella, Italy
7. Fondo Edo Tempia, Biella, Italy
8. Romagna Cancer Registry, Istituto Oncologico Romagnolo, Forlì, Italy