Inflammatory bowel disease (IBD) diagnosis during childhood or adolescence may be linked with an increased risk for developing cancer, compared to the general population, according to results of a Danish and Finish population-based study.
The study “The incidence of cancer and mortality in paediatric onset inflammatory bowel disease in Denmark and Finland during a 23‐year period: a population‐based study” was published in the journal Alimentary Pharmacology & Therapeutics.
Whether IBD increases the risk for colorectal cancer has been debated for a long time, with studies reporting different results.
Very few, however, have looked into the association between pediatric onset of IBD and the risk for cancer. The only two population-based studies done until now have reported an increased risk for colorectal cancer.
A group of researchers at the Copenhagen University Hospital performed a retrospective analysis of data from a population-based registry in Denmark and Finland to assess the estimated risk of cancer and mortality for early IBD.
The analysis included IBD patients diagnosed before turning 18 years old from January 1992 to December 2014.
In the 23-year period, researchers identified a total of 6,689 patients with pediatric onset of IBD — 3,333 in Denmark, and 3,357 in Finland. Patients’ mean age at diagnosis was 14 years and were followed for a median of 9.6 years.
During follow-up, 720 patients underwent surgery to remove the colon (a colectomy). The surgery was done on average within 2.8 years of the IBD diagnosis. A total of 1,365 patients (20.4%) underwent bowel resection (including colectomy) at a median of 2.6 years after diagnosis.
During this time, a total of 72 cases of cancer occurred (38 and 34 in Denmark and Finland, respectively), which included colorectal cancer, small bowel, liver, and skin cancers, and lymphomas.
The standardized cancer incidence ratio for pediatric IBD was 2.5 and reached 75.8 per 10 000 patients within 20 years of follow-up. The median age at cancer diagnosis was 25 years.
For Crohn’s disease (CD), the standardized cancer incidence was 2.6, and 2.5 for ulcerative colitis (UC) .
“We found a 2.5‐fold increase in the risk of cancer in [pediatric] IBD compared to the general population with identical risk estimates in CD and UC,” researchers wrote.
For colorectal cancer specifically, the increased risk was 15.3 times higher in children with IBD compared to the general population. For small bowel cancer and liver cancer, the risk was increased 21.8 and 42.8 times, respectively.
A total of 65 patients died (29 patients and 36 patients in Denmark and Finland, respectively) during the study follow-up, at a median age of 22 years. Cancer was one of the leading causes of death, followed by suicide and infections.
Overall, “we found an increased risk of both cancer and mortality in pediatric IBD with cancer presentation from the late teens and early adulthood,” researchers wrote.
“This adds to the mounting evidence that [pediatric] IBD is a distinct IBD phenotype and should be appreciated as a disease modifier predicting a more aggressive disease course compared to adult onset IBD,” the study concluded.