Screening colonoscopy intervals in familial colorectal cancer

Colorectal cancer (CRC) is one of the top causes of cancer death throughout the world, but it is also one of the most preventable through early detection and removal of premalignant polyps. CRC arises via various genetic and epigenetic changes which alter normal mucosa giving rise to polyps and eventual cancers. This has been well characterized for both the adenoma-to-carcinoma sequence (1) and the serrated polyp oncogenic pathway (2). There is strong evidence that regular colonoscopy and removal of premalignant polyps reduces the incidence of and death from CRC in the average risk population (3) and in hereditary conditions such as Lynch syndrome (4,5). CRC screening guidelines are well established for average risk populations, and for high-risk population such as those associated with hereditary syndromes. However, there is an intermediate risk group with family history of CRC, but without a defined syndrome, that is not as well characterized.