Methotrexate and Melanoma Risk: Is there a Link?

Methotrexate (MTX) is frequently used as an immunosuppressive drug to treat conditions such as psoriasis, psoriatic arthritis (PsoA) and rheumatoid arthritis (RA). Due to the immunosuppressive nature of MTX, there have been some concerns that the use of MTX may raise a person’s risk of developing cutaneous malignant melanoma (CMM).

An Australian study conducted in 2008 showed that patients with RA treated with MTX showed a threefold increase of invasive malignant melanoma compared with the general population. However, there are no other studies that have showed the same results.

In a recent study, a large cohort of patient records were examined to compare more than 100,000 MTX-exposed patients with over 500,000 MTX-unexposed age- and sex-matched patients. In the MTX-exposed group, 591 developed CMM in the time period 2005–2014 while in the MTX-unexposed group, the corresponding number was 2506. These results suggest a small increased risk for developing CMM in patients treated with MTX. This risk is much lower than suggested by the previous Australian study and after analyzing subgroups, the increased risk was significant only in women who were older than 70 years at the start of treatment with MTX.

The authors note a few limitations with interpreting the data. First, Australia has a significantly higher ultraviolet radiation (UVR) index compared to Sweden and a higher overall incidence of CMM. Thus, the difference in UV exposure could have influenced the association of MTX and CMM. In addition this retrospective study design did include data on known risk factors such as skin type, history of sunburn, and the patients in the MTX-unexposed group were not geographically matched to the patients with MTX exposure. Despite these limitations, the authors conclude that the overall risk increase for CMM in MTX-exposed patients observed in this study is modest. It is then worth considering whether the risk is clinically relevant in everyday medical practice when determining whether to use MTX.


Byline: Martha L. Sikes, MS, RPh, PA-C

Posted: July 10, 2017

Source: Wiley Online Library
Adapted from the original article.

[Image: Shutterstock]

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