1. First Department of Surgery, “Laikon” General Hospital, National and Kapodistrian University of Athens, 115 27 Athens, Greece
2. Department of Thoracic Surgery, “Attikon” University Hospital, National and Kapodistrian University of Athens, 124 62 Athens, Greece
3. Department of Surgery, University Hospital of Ioannina, 451 10 Ioannina, Greece
4. Third Department of Surgery, “Attikon” University Hospital, National and Kapodistrian University of Athens, 124 62 Athens, Greece