Oct. 01, 2025
Individuals with Crohn's disease (CD) who have ileal or any small bowel involvement are at increased risk of developing small bowel adenocarcinoma. The absolute risk of small bowel neoplasm (SBN) in this population is believed to be quite low, so screening is not currently recommended. However, experts note that there is a lack of information on this rare, but potentially fatal complication of CD. Mayo Clinic researchers sought to address this knowledge gap by conducting a case-control study examining the clinical features, outcomes and incidence of SBN in this patient population. The results of this study were published in Crohn's & Colitis 360 in 2025.
Methods
Using bioinformatics and natural language processing tools, as well as anatomic pathology records, the researchers identified 54 individuals with CD and SBN and 108 individuals with CD without SBN. All of these individuals were age 18 or older and diagnosed with CD at Mayo Clinic between January 1992 and May 2023. Within this cohort of patients with CD, 55.6% had ileal CD and 59.3% had CD with stricturing phenotype.
Results
Key data points shared by the researchers include the following:
- The nonpenetrating/nonstricturing phenotype of CD was significantly associated with an increased odds of SBN: odds ratio (OR), 9.23; 95% confidence interval (CI); P = 0.0008.
- History of tobacco use (OR, 0.27; 95% CI; P = 0.0011) and IBD-associated colonic neoplasia (OR, 0.18; 95%, CI; P = 0.0303) was associated with a reduced risk of SBN development.
- The median duration of CD before SBN diagnosis in all patients with CD was 19.5 years.
According to Siri A. Urquhart, M.D., lead author on the study publication, the study findings suggest a need for heightened surveillance and awareness of SBN in individuals diagnosed with CD, especially among patients with identified risk factors. Dr. Urquhart is a researcher and gastroenterologist at Mayo Clinic in Rochester, Minnesota.
"We observed that nonpenetrating/nonstricturing and stricturing-only Crohn's disease may be associated with increased odds of developing small bowel neoplasia, while penetrating disease did not seem to be a risk factor," says Dr. Urquhart. "This may be a result of longer disease course before the development of complications, less need for surgical resection and/or possible undertreatment."
"We observed that nonpenetrating/nonstricturing and stricturing-only Crohn's disease may be associated with increased odds of developing small bowel neoplasia, while penetrating disease did not seem to be a risk factor."
Dr. Urquhart also commented on the specific risk factors that were associated with a reduced risk of SBN development. "Smoking predisposes individuals to the development of stricturing and/or penetrating disease, and colorectal neoplasia often results in more-frequent surveillance," explains Dr. Urquhart.
Dr. Urquhart notes that additional studies with larger sample sizes are needed to determine true incidence and risk factors associated with SBN in patients with CD, and to assess the potentially protective effects of early surgery in this patient population.
For more information
Urquhart SA, et al. Clinical characteristics and outcomes of small bowel neoplasms in Crohn's disease: A case-control study. Crohn's & Colitis 360. In press.
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