1. Department of Gastroenterology and Hepatology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands. 1
2. Department of Surgery, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands. 2
3. Department of Otorhinolaryngology and Head and Neck Surgery, Center for Optical Diagnostics and Therapy, Erasmus Medical Center, Rotterdam, the Netherlands. 3
4. Department of Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands. 4