Risk of Colorectal Cancer and Adenomas in the Families of Patients With Adenomas

BACKGROUNDGuidelines recommend that individuals with a first-degree relative (FDR) diagnosed with colorectal cancer (CRC) or advanced adenoma before age 60 years should undergo colonoscopy starting at age 40 years. The authors quantified the risk of adenomas and CRC in FDRs, second-degree relatives (SDRs), and third-degree relatives (TDRs) of patients diagnosed with adenomas and advanced adenomas. METHODSA population-based, retrospective, case-control study was performed of residents of the state of Utah aged 50 years to 80 years who underwent colonoscopy between 1995 and 2009 at Intermountain Healthcare or the University of Utah. Controls were selected from the population of colonoscopy patients who were free of adenomas or CRC and matched to each case based on sex and birth year. Colonoscopy results were linked with cancer and pedigree information from the Utah Population Database to investigate the familial aggregation of adenomas and CRC using Cox regression analysis. The unit of analysis was the relatives of cases and controls. RESULTSOf 126,936 patients who underwent colonoscopy, 43,189 had adenomas and 5563 had advanced adenomas and defined the case population. An elevated risk of CRC was found in FDRs (relative risk [RR], 1.35; 95% confidence interval [95% CI], 1.25-1.46), SDRs (RR, 1.15; 95% CI, 1.07-1.23) of adenoma cases, and in FDRs of advanced adenoma cases (RR, 1.68; 95% CI, 1.29-2.18) compared with controls. Approximately 10% of CRCs diagnosed in relatives would have been missed if the current screening guidelines were strictly adhered to. CONCLUSIONSRelatives of colonoscopy patients with adenomas and advanced adenomas appear to have a significantly elevated risk of developing colorectal neoplasia. These data should be considered when establishing CRC screening guidelines for individuals and their families. Cancer 2014;120:35-42. (c) 2013 American Cancer Society. This population-based study of 126,936 individuals from Utah who underwent colonoscopy found that relatives of patients with adenomas and advanced adenomas had an increased risk of colorectal cancer and adenomas compared with relatives of unaffected controls. Although first-degree relatives were at the greatest risk, an elevated risk of colorectal neoplasia could be detected out to distant third-degree relatives.