Colorectal cancer (CRC) is the third most common cancer in the UK: incidence increases with age, median age at diagnosis being over 70 years. Approximately 25% of cases occur in individuals with a family history of CRC, including 5% caused by familial adenomatous polyposis (FAP) or hereditary non-polyposis CRC (HNPCC). Most develop from adenomatous polyps arising from the intestine lining. Individuals with these polyps undergo polypectomy and are invited for endoscopic surveillance. Screening via faecal occult blood testing has been rolled out across the UK