1. Gastroenterology Department, Fernando Pessoa Teaching Hospital , Porto , Portugal
2. Precancerous Lesions and Early Cancer Management Research Group RISE@CI-IPO [Health Research Network], Portuguese Oncology Institute of Porto [IPO-Porto] , Porto , Portugal
3. Homerton Anogenital Neoplasia Service, Homerton University Hospital , London , UK
4. Institute for Global Health, University College London , London , UK
5. Gastroenterology Department, St. James’s University Hospital , Leeds , UK