Children who are diagnosed with inflammatory bowel disease (IBD) are more than twice as likely to develop cancer, especially gastrointestinal cancer, later in life compared with the general pediatric population, a new meta-analysis suggests.
Although the overall incidence rate of cancer in this population is low, “we found a 2.4-fold increase in the relative rate of cancer among patients with pediatric-onset IBD compared with the general pediatric population, primarily associated with an increased rate of gastrointestinal cancers,” wrote senior author Tine Jess, MD, DMSci, Aalborg University, Copenhagen, and colleagues.
The study was published online March 1 in JAMA Network Open.
Previous research indicates that IBD is associated with an increased risk for colon, small bowel, and other types of cancer in adults, but the risk among children with IBD is not well understood.
In the current analysis, Dr. Jess and colleagues examined five population-based studies from North America and Europe, which included more than 19,800 participants with pediatric-onset IBD. Of these participants, 715 were later diagnosed with cancer.
Overall, the risk for cancer among individuals with pediatric-onset IBD was 2.4-fold higher than that of their peers without IBD, but those rates varied by IBD subtype. Those with Crohn’s disease, for instance, were about two times more likely to develop cancer, while those with ulcerative colitis were 2.6 times more likely to develop cancer later.
Two studies included in the meta-analysis broke down results by sex and found that the risk for cancer was higher among male versus female patients (pooled relative rates [pRR], 3.23 in men and 2.45 in women).
These two studies also calculated the risk for cancer by exposure to thiopurines. Patients receiving these immunosuppressive drugs had an increased relative rate of cancer (pRR, 2.09). Although numerically higher, this rate was not statistically higher compared with patients not exposed to the drugs (pRR, 1.82).
When looking at risk by cancer site, the authors consistently observed the highest relative rates for gastrointestinal cancers. Specifically, the investigators calculated a 55-fold increased risk for liver cancer (pRR, 55.4), followed by a 20-fold increased risk for colorectal cancer (pRR, 20.2), and a 16-fold increased risk for small bowel cancer (pRR, 16.2).
Despite such high estimates for gastrointestinal cancers, “this risk corresponds to a mean incidence rate of 0.3 cases of liver cancer, 0.6 cases of colorectal cancer, and 0.1 cases of small bowel cancer per 1,000 person-years in this population,” the authors noted.
In other words, “the overall incidence rate of cancer in this population is low,” at less than 3.3 cases per 1,000 person-years, the authors concluded.
Relative rates of extraintestinal cancers were even lower, with the highest risks for nonmelanoma skin cancer (pRR, 3.62), lymphoid cancer (pRR, 3.10), and melanoma (pRR, 2.05).
The authors suggest that identifying variables that might reduce cancer risk in pediatric patients who develop IBD could better shape management and prevention strategies.
CRC screening guidelines already recommend that children undergo a colonoscopy 6-8 years after being diagnosed with colitis extending beyond the rectum. Annual colonoscopy is also recommended for patients with primary sclerosing cholangitis from the time of diagnosis and annual screening for skin cancer is recommended for all patients with IBD.
The investigators further suggest that because ongoing inflammation is an important risk factor for cancer, early and adequate control of inflammation could be critical in the prevention of long-term complications.
The study was supported by a grant from the Danish National Research Foundation. Dr. Jess and coauthors Rahma Elmahdi, MD, Camilla Lemser, and Kristine Allin, MD, reported receiving grants from the Danish National Research Foundation National Center of Excellence during the conduct of the study. Coauthor Manasi Agrawal, MD, reported receiving grants from the National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Diseases during the conduct of the study.
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