IBD in Youth May Double Cancer Risk in Later Life

— Exposure to common treatments did not increase risk

MedpageToday
A mother comforts her son who is in bed with abdominal pain

Pediatric-onset of inflammatory bowel disease (IBD) could double the risk of developing cancer in adulthood, a Canadian study suggested.

The population-based case-control analysis revealed that 1.7% of patients with childhood-onset IBD developed cancer, as compared with 0.8% of controls (HR 2.00, 95% CI 1.16-3.43), reported Wael El-Matary, MD, MSc, of the University of Manitoba in Winnipeg, and colleagues.

This translated to overall cancer rates of 114 and 57 per 100,000 person-years, respectively, as shown in the study online in Gastroenterology.

Crohn's disease patients compared with controls had an HR for developing later cancers of 2.47 (95% CI 1.31-4.66), while in those with ulcerative colitis, the risk was not significantly increased (HR 1.24, 95% CI 0.43-3.59).

Between those in the IBD group who developed cancer and those who did not, there was no significant difference in exposure to two or more dispensations of thiopurines (odds ratio [OR] 0.43, 95% CI 0.10-1.77) or anti-tumor necrosis factor agents (OR 0.56, 95% CI 0.10-3.26).

Jessica Philpott, MD, PhD, of the Cleveland Clinic in Ohio, told MedPage Today that the study addresses the important question of long-term outcomes in patients who develop IBD as children.

"While a twofold increase is certainly of concern, thankfully because the risk of developing cancer at a young age is so low, there is still a very low risk that patients with IBD will develop cancer -- 114 per 100,000 patient-years," said Philpott, who was not involved with the study. "If you double a number that is small, it is still not a large number."

Philpott added that the lack of association between cancer and common therapies such as thiopurines and biologics was reassuring. "From this study alone, we cannot easily derive ways to decrease the cancer rate, but having more studies like this will be important to continue to improve the long-term outcomes of our patients," she said.

The association between IBD and gastrointestinal cancers is considered to be due to intestinal inflammation, and for IBD and extra-intestinal cancers such as lymphoma and leukemia, to be related to impaired immune surveillance for malignancy, the researchers explained. They added that while younger age at IBD diagnosis has been recognized as a risk factor for developing colorectal cancer, it has not been clear if the risk is the same for extra-intestinal malignancy.

The team noted that a 2017 analysis from the DEVELOP clinical cohort reported 15 cancers and five cases of hemophagocytic syndrome in 5,766 children with IBD who were followed for 9 years. Infliximab (Remicade) exposure was not associated with this syndrome or malignancy.

In 2017, a Swedish study found a similarly elevated risk of adult cancer in IBD patients diagnosed as children, as well as almost three times the risk of developing cancer before age 18. And in 2018, another analysis from Sweden reported that as adults, children diagnosed with IBD run three times the risk of death as members of the general population.

For the current study, El-Matary's group examined databases from the province of Manitoba, including children diagnosed with IBD before age 18 and their counterpart controls, who were followed for 14,938 and 132,202 person-years, respectively. Cancers diagnosed in cases and controls were compared from 1984 to 2018.

In all, 17 cancer cases occurred in 947 childhood-onset IBD patients and 75 occurred among the 9,272 controls. Cancers in the IBD group included colorectal, non-melanoma skin cancers, lymphoma, leukemia, and bladder cancer.

Median age at IBD diagnosis was 14 (interquartile range [IQR] 12-16). The median age at cancer diagnosis in persons with IBD was 37 (IQR 24-45).

Study limitations, the researchers said, included the small number of incident cancers and the possibility of misclassification bias.

  • author['full_name']

    Diana Swift is a freelance medical journalist based in Toronto.

Disclosures

El-Matary reported financial relationships with Janssen Canada and AbbVie Canada; co-authors reported financial relationships with AbbVie Canada, Ferring Canada, Janssen Canada, Napo Pharmaceuticals, Pfizer Canada, Shire Canada, Takeda Canada, Mylan Pharmaceuticals, Amgen, Pendopharm, Takeda Canada, Guardant Health, and Merck Canada.

Philpott reported a financial relationship with AbbVie.

Primary Source

Gastroenterology

Source Reference: El-Matary W, et al "Long-term cancer risk in patients with pediatric-onset inflammatory bowel diseases in the Canadian population" Gastroenterol 2020; doi.org/10.1053/j.gastro.2020.03.048.