Family History Associates With Increased Risk of Colorectal Cancer in Patients With Inflammatory Bowel Diseases.

Background & Aims: Individuals with inflammatory bowel diseases (IBDs) have an increased risk of developing colorectal cancer (CRC). Although family history of CRC is a well-established risk factor in healthy individuals, its role in patients with IBD is less clear. We aimed to estimate the risk of CRC in a cohort of patients with IBD from Utah and the significance of family history of CRC in a first-degree relative (FDR).

Methods: We identified Utah residents with IBD, using the Intermountain Healthcare and University of Utah Health Sciences databases, from January 1, 1996, through December 31, 2011. CRCs were identified using the Utah Cancer Registry and linked to pedigrees from the Utah Population Database. CRC incidence was compared with that of the state population by standardized incidence ratios (SIRs).

Results: A cohort of 9505 individuals with IBD was identified and 101 developed CRC during the study period. The SIR for CRC in patients with Crohn's disease was 3.4 (95% CI, 2.3-4.4), and in patients with ulcerative colitis was 5.2 (95% CI, 3.9-6.6). Patients with IBD and a concurrent diagnosis of primary sclerosing cholangitis had the greatest risk of CRC (SIR, 14.8; 95% CI, 8.3-21.2). A history of CRC in a FDR was associated with a nearly 8-fold increase in risk of CRC in patients with IBD (SIR, 7.9; 95% CI, 1.6-14.3), compared with the state population.

Conclusions: Patients with IBD have a 3- to 5-fold increase in risk of CRC, and those with CRC in a FDR have an almost 8-fold increase in risk. Family history may act as a simple measure to identify individuals with IBD at highest risk for CRC and indicates the need for enhanced surveillance in this population.