Adenomas as a risk factor in familial colorectal cancer: implications for screening and surveillance in the U (Lynch Syndrome)

Abstract

 Colorectal cancer (CRC) develops from normal epithelium, through dysplastic adenoma to invasive carcinoma. In addition to familial adenomatous polyposis and Lynch syndrome, approximately 10-35% of CRCs are familial in nature. CRC screening and surveillance programmes are based on an understanding of polyp natural history and rely on the ability to remove pre-malignant lesions endoscopically before they are capable of developing invasion. There are however significant differences in these guidelines between the United Kingdom (UK) and the United States of America, in relation to the weight attributed to a family history of polyps. Here we show using publicly available national data sets that these guideline differences unexpectedly generate inadequate screening recommendations for second-degree relatives of patients with CRC in the UK. We validate our simple mathematical modelling of the clinical problem on a regional data set as well as previously published study data to demonstrate correct interpretation. We further discuss the implications of a family history of adenoma formation in the contemporary climate of the Bowel Cancer Screening Programme and suggest a re-evaluation of the UK guidelines in the light of this developing issue.