Family history as a risk factor for colorectal cancer in inflammatory bowel disease

Background & Aims: Familial colorectal cancer (CRC) is a risk factor for CR C in healthy individuals and, as indicated by case-control studies, possibl y in ulcerative colitis. Little is known about the cancer risk in familial inflammatory bowel disease (IBD), We assessed the significance of familial CRC, or IBD, on the risk for CRC in patients with IBD, Methods: Population- based cohort study of 19,876 individuals with ulcerative colitis or Crohn's disease born between 1941 and 1995, Registry-based follow-up and assessmen t of familial CRC, and IBD, Risk of CRC assessed as incidence proportion (" absolute risk," IP) and relative risk (RR), Results: Familial CRC was assoc iated with a more than 2-fold risk of CRC (adjusted RR = 2.5, 95% confidenc e interval 1.4-4.4) and an increase in the IP of CRC at 54 years of age fro m 3.8% to 6.9%, Patients with a first-degree relative diagnosed with CRC be fore 50 years of age had a higher RR (9.2, 95% confidence interval 3.7-23) and the highest IP (29%), No association with familial IBD was observed. Co nclusions: Information on family history of CRC may be a simple way to iden tify individuals with IBD at elevated risk of developing CRC.