Background
Guidelines on colorectal cancer (CRC) screening recommend screening of average-risk adults only. In addition, screening of individuals with active inflammatory bowel disease (IBD) might result in too many false-positive cases. However, the organisers of CRC screening programmes are often uninformed of whom to exclude due to an elevated CRC risk or active IBD. It is therefore unknown how often high-risk individuals (i.e. individuals with a previous diagnosis of CRC or polyps associated with hereditary CRC syndromes and certain patient groups with a diagnosis of inflammatory bowel disease (IBD) or multiple polyps) and individuals with active IBD participate in CRC screening following invitation.