1. NOVA Medical School/Faculdade de Ci�ncias M�dicas, Universidade Nova de Lisboa, 1169‑056 Lisbon, Portugal
2. Department of Gastroenterology, Instituto Portugu�s de Oncologia de Lisboa Francisco Gentil (IPOLFG), 1099‑023 Lisbon, Portugal
3. Department of Surgery, Instituto Portugu�s de Oncologia de Lisboa Francisco Gentil (IPOLFG), 1099‑023 Lisbon, Portugal