No link between TNF-a inhibitor use and cancer in inflammatory bowel disease

1. In this cohort study, use of TNF-a inhibitors in inflammatory bowel disease patients was not associated with an increased risk of malignancy. 

2. While a modest increased risk of malignancy was observed among those taking TNF-a inhibitors when compared to individuals who never took TNF-a inhibitors, there was no evidence of an increased risk after further controlling for azathioprine use. 

Evidence Rating Level: 2 (Good)            

Study Rundown: Inflammatory bowel disease (IBD) is often treated with tumor necrosis factor-alpha (TNF-a) inhibitors, including infliximab, adalimumab, and certolizumab pegol.  There is controversy regarding the relationship between TNF-a inhibitors and malignancy, with some trials pointing towards an increased risk of malignancy with TNF-a inhibitors use. This study included 4,553 individuals with IBD who took TNF-a inhibitors and 51,593 individuals with IBD who did not take TNF-a inhibitors and explored the association between TNF-a inhibition and malignancy. After adjusting for various factors including other medications used and disease duration, there was no increased risk of cancer among those taking TNF-a inhibitors. There was also no increased risk when specific body sites such as colorectal, skin, and hematopoietic and lymphoid tissue were examined individually.  Strengths of this study include the large number of participants and the relatively long follow up time.  Data was extracted from several databases, allowing for the most complete information possible.  There was also an allowance of a lag period before malignancy data was collected to avoid including malignancies that may have existed before exposure to TNF-a inhibition.  Weaknesses of the study include the relatively low case numbers and the inability to study individual medications separately.  Ultimately, this study argues against a relationship between TNF-a inhibitors and malignancy, but a large prospective cohort study would be helpful in exploring this question further.

Click to read the study, published today in JAMA

Relevant Reading: Tumor necrosis factor α inhibitor therapy and cancer risk in chronic immune-mediated diseases

In-Depth [retrospective cohort]: This study explored the relationship between TNF-a inhibitors and malignancy in 4,553 individuals with IBD who took TNF-a inhibitors and 51,593 individuals with IBD who did not take TNF-a inhibitors in Denmark.  Individuals exposed to TNF-a inhibitors had a median of 3.7 years (IQR 1.8-6.0) of follow up time, received a median of 8 doses (IQR 3-17), and had a median age of 33.7 years (SD 13.9).  After adjusting for various time dependent factors and many mediations, there was a modest increased risk of malignancy among those taking TNF-a inhibitors (RR 1.25 (95% CI 1.00-1.58)).  However, after further controlling for azathioprine use, there was no increased risk of malignancy (RR 1.07 (0.85-1.36)).  This is consistent with previous data suggesting an increased risk of malignancy in individuals using azathioprine.  Further analysis was performed on specific subtypes of cancer including colorectal cancer, melanoma, and hematopoietic and lymphoid malignancies and found no increased risk of cancer in any specific site.

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