Lymphoma risk is slightly elevated in patients with IBD

The risk of developing lymphoma is slightly elevated in inflammatory bowel disease (IBD) and has increased in recent years in patients with Crohn's disease, report researchers from Karolinska Institutet in a study published in Clinical Gastroenterology and Hepatology. The researchers could see a risk increase in patients taking modern IBD drugs and, less so, in patients not on such drugs, indicating that the lymphoma risk could be affected by both the medication and the disease activity itself.

Inflammatory bowel disease (IBD), which includes Crohn's disease and ulcerative colitis, is a chronic intestinal inflammation that can increase the risk of developing lymph node cancer (lymphoma), a disease that affects the immune system.

Previous studies of the lymphoma risk of IBD have been too small to draw reliable conclusions. The studies have not taken into account of important systematic errors or been representative of today's IBD patients."

Ola Olén, study's first author, consultant and docent at the Department of Medicine (Solna), Karolinska Institutet

The present study included almost 170,000 IBD patients identified in Swedish and Danish national registries between 1969 and 2019. Comparing these patients with a matched population without IBD in order to calculate the risk of lymphoma, the researchers discovered that patients with both Crohn's disease and ulcerative colitis had a higher risk of lymphoma. The risk was highest, however, in patients with Crohn's disease, the increase being driven mainly by T-cell lymphoma and aggressive B-cell lymphoma.

"We found an elevated relative risk of different types of lymphoma in both Crohn's disease and ulcerative colitis, but we need to point out that the absolute risk is very low," says the study's last author Jonas F Ludvigsson, consultant and professor at the Department of Medical Epidemiology and Biostatistics, Karolinska Institutet.

"The increase in risk equates to only one extra case of lymphoma in 1,000 people with IBD, who were followed for ten years."

The risk of lymphoma has increased in patients with Crohn's disease over the past two decades, which coincides with the increasing use of immunomodulating drugs for IBD. While the highest risk of developing the cancer was observed in patients who had received these drugs, the researchers found that patients who were not on such medication were also at a higher risk of lymphoma.

"This finding indicates that both the inflammation in itself and its treatment play a part," says Dr Olén. "Since there's a lot of talk about the lymphoma risk associated with immunomodulating drugs, it's important to make it clear that also the disease and the inflammation per se seem to drive the development of lymphoma. One has to take account of this and discuss it when prescribing modern treatments where there might be a concern that they will increase the risk of lymphoma."

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"We now want to use more detailed data to answer the question about what's most important in terms of the lymphoma risk - the disease itself or its treatment," says Dr Olén.

Many of the researchers have previously received research grants via their universities from different pharmaceutical companies; however, no such grants were received for this present study.