A new review of research into inflammatory bowel disease (IBD) treatments has found that certain medicines, particularly a type called thiopurines and a class known as anti-tumour necrosis factor (anti-TNF) medicines, are linked to a higher risk of some cancers. The findings may help patients and their doctors think through the benefits and risks of different treatment options for Crohn’s disease and ulcerative colitis.
Background
People with IBD now have access to a wide range of treatments, from older drugs such as thiopurines to newer biologic and targeted therapies, including anti-TNF medicines, Janus kinase (JAK) inhibitors, interleukin-23 (IL-23) inhibitors, and sphingosine-1-phosphate (S1P) receptor modulators. These medicines work by calming an overactive immune response, but researchers have long asked whether reducing immune activity over long periods might also raise the risk of certain cancers.
What the Review Found
Researchers combined results from 28 published studies to look at cancer risk across these different treatments.
Thiopurines
The review reported that people taking thiopurines had a notably higher risk of cancer compared with those not taking them, and a higher risk compared with people taking anti-TNF medicines instead. Lymphoma, a cancer affecting the immune system, was also more common in people taking thiopurines alone. A separate analysis combining several studies found this risk was highest in people currently taking the medicine, in those under 30, and in men.
Anti-TNF medicines
Two large registry studies did not find a significant increase in overall cancer risk with anti-TNF medicines alone. However, one study linked anti-TNF use to a higher lymphoma risk, and a combined analysis of several studies also reported a modestly higher rate of lymphoma with this treatment class.
Combining thiopurines and anti-TNF medicines
Taking a thiopurine and an anti-TNF medicine together appeared to carry a higher risk than either drug alone, with lymphoma risk more than double that seen with either medicine used by itself. This combination was also linked to a higher risk of nonmelanoma skin cancer, a common and usually treatable form of skin cancer.
JAK inhibitors
People taking JAK inhibitors had a higher cancer risk than those taking anti-TNF medicines, but no higher risk than people taking a placebo (an inactive treatment used for comparison in trials).
Vedolizumab, ustekinumab and S1P receptor modulators
The review found no evidence that vedolizumab, ustekinumab, or S1P receptor modulators increased cancer risk, including among people who had previously had cancer.
IL-23 inhibitors
There was not enough evidence available to draw firm conclusions about IL-23 inhibitors and cancer risk.
Why This Matters
These findings may help explain why some IBD treatment decisions take personal cancer history and risk factors into account. The authors noted that thiopurines showed the most consistent link to cancer risk, with the strongest signal for lymphoma seen when thiopurines were combined with anti-TNF medicines.
What to Keep in Mind
The researchers cautioned that most of the underlying studies were observational, meaning they could not prove that the medicines directly caused cancer. Many studies also involved small numbers of cancer cases, varied patient backgrounds, and limited follow-up time. Further research is needed to confirm these patterns and to better understand risk with newer treatments.
Reference
Kaur G, Jain R, Grover P, Yasin Z, Singh K, Singh B. Systematic review of malignancy risk with biologic, advanced small-molecule, and thiopurine therapies for inflammatory bowel disease. Gastrointest Disord. 2026;8(3):38. doi:10.3390/gidisord8030038
This article is a journalistic summary for informational purposes only. It does not constitute clinical advice or a recommendation to alter treatment decisions.