1. Hepatobiliary and Pancreatic Surgery (HPB) Unit, Department of Surgery, University Hospital of Ioannina and Faculty of Medicine, School of Health Sciences, University of Ioannina, 451 10 Ioannina, Greece
2. Second Department of Surgery, General University Hospital of Alexandroupolis and Medical School, Democritus University of Thrace, 691 00 Alexandroupoli, Greece
3. Department of Oncology, University Hospital of Ioannina and Faculty of Medicine, School of Health Sciences, University of Ioannina, 451 10 Ioannina, Greece
4. Laboratory of Hygiene and Epidemiology, Faculty of Medicine, University of Thessaly, 382 21 Larisa, Greece