This study has an international multi-centre prospective cohort design. The study will be directed by the Academic Medical Centre (AMC), Amsterdam, the Netherlands.
Population base All patients treated at one of the participating centres will be eligible for this study.
Protocol violations Incomplete endoscopic excision of polyps without proper re-colonoscopy Prolonged interval within surveillance colonoscopies (Exceeding protocol with \>1 year)
Sample size calculation No sample size calculation is performed, because of the observational design of this study. All eligible patients will be included, unless an exclusion criterion is met. The envisioned number of patients to be included is around 500.
Institutional review board This study is conducted in accordance with the research code of our Institutional Review Board (IRB) on human experimentation as well as in agreement with the Helsinki Declaration. The IRB decided that the study did not apply to the requirements of the Medical Research Involving Human Subjects Act (WMO), as data were collected during routine care and no additional patient interventions will be undertaken. Therefore also no informed consent is needed for this study. The study protocol will be registered on a publicly accessible website register.
