1. Gastroenterology and Hepatology Department, Endoscopy Unit Puerta de Hierro University Hospital, Majadahonda, Madrid, Spain
2. IDIPHISA-Instituto de Investigación Segovia Arana
3. Gastrointestinal Surgery Department. Puerta de Hierro University Hospital, Majadahonda, Madrid, Spain
4. Pathology Department. Puerta de Hierro University Hospital, Majadahonda, Madrid, Spain