PTH-339 Polypectomy in patients with a family history of colorectal cancer may lead to a decreased surveillance (and ultimately a small number of missed cancers) in their kindred

Introduction Colorectal cancer (CRC) is likely to be prevented by polypectomy. However, polypectomy in first degree relatives of patients with familial CRC may lead to a weaker subsequent family history and potentially inadequate surveillance recommendations for further generations. Method We have proposed a simple model to investigate how many colorectal cancers may potentially develop per annum in the UK if a known family history of colorectal cancer is diluted by future polypectomy in first degree relatives of patients with familial CRC, leading to reduced subsequent surveillance of the next generation. Statistics on the incidence of familial CRC and risk of CRC in relation to family history were retrieved from the literature. 1,2 Results There are approximately 41581 cases of CRC in the UK per annum and it is assumed that 4158 (10%) of cases are familial in origin. If each familial case were to have had two children and they were ultimately offered a colonoscopy (with possible polypectomy), then 748 CRC (9%) may be prevented. This could lead to 1497 subsequent offspring being “at risk” of a familial CRC but not being offered screening with current guidelines. This could potentially lead to the development of 135 cases (9%) of CRC from inadequate surveillance. Conclusion Here we show that current UK guidelines on endoscopic screening of patients with a family history of colorectal cancer (which do not regard polyps as a familial risk factor) result in approximately 135 preventable cases of CRC per annum. Given the small effect size, a formal study to show benefit of enhanced screening in this group is unfeasible. Awareness of this concept will enable screening to be advised on a case by case basis. Disclosure of interest None Declared. References Johns LE, Houlston RS: A systematic review and meta-analysis of familial colorectal cancer risk. Am J Gastroenterol. 2001;96(10):2992–3003 Surveillance, Epidemiology, and End Results Program. http://seer.cancer.gov/