Department of Gastroenterology, Faculty of Medicine, Centro Hospitalar São João, Porto, Portugal fm@med.up.pt. Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, Porto, Portugal. Department of Gastroenterology, Faculty of Medicine, Centro Hospitalar São João, Porto, Portugal. Department of Pathology, Centro Hospitalar São João, Porto, Portugal. Department of Gastroenterology, Centro Hospitalar Universitário de Coimbra, Coimbra, Portugal. Department of Gastroenterology, Centro Hospitalar do Alto Ave, Guimarães, Portugal. Department of Gastroenterology, Centro Hospitalar do Porto, Porto, Portugal. Department of Gastroenterology, Centro Hospitalar Lisboa Oriental Portugal, Lisboa, Portugal. Department of Pathology, Centro Hospitalar Universitário de Coimbra, Coimbra, Portugal. Department of Pathology, Centro Hospitalar do Alto Ave, Guimarães, Portugal. Department of Pathology, Centro Hospitalar do Porto, Porto, Portugal. Department of Pathology, Centro Hospitalar Lisboa Oriental Portugal, Lisboa, Portugal. Clinical Data Unit, Eurotrials Scientific Consultants, Lisboa, Portugal. CIDES Department of Health Information and Decision Sciences, Faculty of Medicine, University of Porto, Porto, Portugal. CINTESIS, Center for Health Technology and Services Research, Porto, Portugal. MedInUP Center for Drug Discovery and Innovative Medicines, University of Porto, Porto, Portugal. Department of Pathology, University Hospital of KU Leuven and UZ Gent, Leuven, Belgium. Institute of Molecular Pathology and Immunology of the University of Porto [Ipatimup], University of Porto, Porto, Portugal.