1. First Propaedeutic Department of Surgery, Hippocration General Hospital, School of Medicine, National and Kapodistrian University of Athens, 11527 Athens, Greece
2. First Department of Surgery, Laikon General Hospital, School of Medicine, National and Kapodistrian University of Athens, 11527 Athens, Greece
3. Division of Hematology and Oncology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA