1. Department of Endoscopy and Surgery, Tenwek Hospital, Bomet, Kenya
2. Department of Surgery; Alpert Medical School of Brown University; Providence, Rhode Island, United States
3. Division of Gastroenterology and Hepatology, Mayo Clinic, Phoenix, Arizona, United States
4. Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States
5. Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, United States