1. University of Perugia; Department of General Surgery; Terni Italy
2. University of Perugia; Department of General Surgery; Perugia Italy
3. Regional Health Authority of Umbria; Health Planning Service; Via Mario Angeloni 61 Perugia Umbria Italy 06124
4. Forlì Hospital; Surgical Oncology; Via C. Forlanini, 34 Forlì Italy 47121
5. Hospital of Terni; Liver Unit and Department of Digestive Surgery; Terni Italy
6. Regional Health Authority of Umbria; Epidemiology Department; Via Mario Angeloni, 61 Perugia Italy 06124