The risk for cancer is significantly elevated in patients with pediatric-onset inflammatory bowel disease (IBD), according to results from a meta-analysis published in JAMA Network Open.

Investigators conducted a systematic search of the MEDLINE and Embase databases from inception through October 2021 for population-based studies providing relative risk estimates for any cancer in patients with pediatric-onset IBD. Study selection and data extraction were performed by 2 separate investigators; risk of bias and study quality were assessed using the Newcastle-Ottawa Scale. A random-effects model meta-analysis was performed to assess the relative rate of cancer overall and by IBD subtype and cancer site. Pooled relative rates (pRRs) were calculated for studies included in the meta-analysis.

A total of 4628 abstracts were identified from the initial search, from which 5 were included in the meta-analysis. The pooled cohort comprised 19,812 patients with pediatric-onset IBD, among whom 715 had a diagnosis of cancer. The reference group included 3,065,282 patients without IBD, among whom 11,195 had cancer. The overall pRR for cancer in the IBD group was 2.46 (95% CI, 2.06-2.93) compared with individuals without IBD. Cancer rates were substantially elevated in each IBD subtype, with pRRs of 2.03 (95% CI, 1.67-2.46) and 2.61 (95% CI, 2.00-3.40) for Crohn disease and ulcerative colitis, respectively. The reported incidence rate of any cancer in the IBD population ranged from 1.0 to 3.3 cases per 1000 person-years.


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Three studies reported relative rates by cancer type. The highest relative rates by cancer subtype were for gastrointestinal (GI) cancers, with a 55-fold increased rate of liver cancer (pRR, 55.45; 95% CI, 19.59-156.99), a 20-fold increased rate of colorectal cancer (pRR, 20.29; 95% CI, 15.90-25.90), and a 16-fold increased rate of small bowel cancer (pRR, 16.20; 95% CI, 3.52-74.66). Relative rates of extraintestinal cancers were lower, though remained elevated for nonmelanoma skin cancer (pRR, 2.63; 95% CI, 1.97-6.66), lymphoid cancer (pRR, 3.10; 95% CI, 1.88-5.10), and melanoma (pRR, 2.05; 95% CI, 1.27-3.29).

Results from this meta-analysis highlight the substantially elevated rate of cancer in patients with pediatric-onset IBD. The risk was particularly high for GI cancers. As study limitations, investigators noted the absence of data on IBD severity and IBD therapy exposure. More granular data on cancer subtypes were also lacking.  

“This meta-analysis of unselected, population-based studies showed a greater than 2-fold increased rate of cancer among patients with pediatric-onset IBD compared with the general pediatric populations, primarily owing to an increased rate of [GI] cancers,” the study authors wrote. “Identifying variables that modulate cancer risk in pediatric patients would be valuable for targeting prevention and screening.”

Reference

Elmahdi R, Lemser CE, Thomsen SB, Allin KH, Agrawal M, Jess T. Development of cancer among patients with pediatric-onset inflammatory bowel disease: a meta-analysis of population-based studies. JAMA Netw Open. Published online March 1, 2022. doi:10.1001/jamanetworkopen.2022.0595