How much does a family history of colorectal cancer (CRC) increase the risk of CRC in IBD?
Clinicians managing patients with IBD should remember to ask about family history of colon cancer when designing dysplasia surveillance protocols.
Samadder NJ, Valentine JF, Guthery S, et al. Family History Associates With Increased Risk of Colorectal Cancer in Patients With Inflammatory Bowel Diseases. Clin Gastroenterol Hepatol. 2019;17(9):1807–13; https://doi.org/10.1016/j.cgh.2018.09.038.
To elucidate the risk of CRC in patients with IBD and a history of CRC in a first-degree relative, researchers in Utah studied data from 9,505 IBD patients included in two large health system and academic medical center databases between 1996 and 2011. They used information from the Utah Cancer Registry to identify CRC cases among these individuals and compared those rates to the CRC incidence found in a separate state-wide, population-based database. The IBD cohort was distributed roughly evenly by IBD type and sex. Roughly 3% of IBD patients had at least one first-degree relative with CRC.
The authors found that 61 ulcerative colitis (UC) patients and 40 Crohn’s disease (CD) patients were diagnosed with CRC during the study period. Analyses determined that patients with CD were 3.4 times more likely to have a CRC diagnosis during the study than the general population (Standardized Incidence Ratio [SIR]: 3.4; 95% Confidence Interval [CI], 2.3–4.4), and UC patients were 5.2 times more likely to have a CRC diagnosis (95% CI, 3.9–6.6). The risk of CRC among IBD patients with a first-degree relative with CRC was almost eight times higher than in the general population (SIR: 7.9; 95% CI, 1.6–14.3).
Analyses examining additional risk factors for CRC revealed patients with IBD and primary sclerosing cholangitis had the highest risk of CRC (SIR: 14.8; 95% CI, 8.3–21.2), compared to the general population.
The risk of CRC was higher among men than women, regardless of IBD type, and right-sided CRC was more common than distal or rectal CRC, for both CD and UC patients.
Study Design: Observational, population-based cohort
Funding: The study was supported by the Crohn’s and Colitis Foundation of America, the National Cancer Institute, the American College of Gastroenterology and the Huntsman Cancer Institute.
Allocation: Not applicable
Setting: Health system databases and statewide registry
Level of Evidence: 2b (Oxford Levels of Evidence)
The summary and conclusion in this issue of E-mentoring in IBD pertains to the manuscript(s) being reviewed, and should be considered in the context of what is already known surrounding the topic and incorporated into practice as deemed appropriate by the individual learner.