1 Division of Gastroenterology and Gastrointestinal Endoscopy, Department of Experimental Oncology, IRCCS San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Milan, Italy.
2 Department of Gastrointestinal Surgery, IRCCS San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Milan, Italy.