Filippos Giannopoulos, Martin Gillstedt, Marta Laskowski, Kasper Bruun Kristensen, Sam Polesie
DOI: 10.2340/00015555-3725

An association between methotrexate use and risk of cutaneous squamous cell carcinoma has been reported in patients with rheumatoid and psoriatic arthritis. A nested case-control study was performed to investigate if methotrexate use among patients with psoriasis was associated with increased risk of cutaneous squamous cell carcinoma. Data were obtained from Swedish registers and included 623 patients with psoriasis and a first cutaneous squamous cell carcinoma from 2010 to 2016. Ten randomly selected patients with psoriasis were matched on age and sex to each case. Among cases, 160 (26%) were ever-users of metho­trexate. The corresponding number among the controls was 1,370 (22%), yielding an unadjusted odds ratio (OR) of 1.23 (95% confidence interval (95% CI) 1.02–1.49); p = 0.034. After adjusting for use of other immunosuppressive drugs the association was close to unity (OR 1.09; 95% CI 0.89–1.34); p = 0.39. The slightly increased risk of cutaneous squamous cell carcinoma associated with methotrexate-exposure in patients with psoriasis does not seem to be associated with metho­trexate, but rather with disease severity, other anti-psoriatic treatments, and ultraviolet exposure.

Squamous cell carcinoma is the second most common type of skin cancer. This study investigated whether use of methotrexate was linked to increased risk of such cancer, using a database of Swedish patients with psoriasis. Among these, patients who developed squamous cell carcinoma were identified and their use of methotrexate compared with cancer-free patients. Patients with squamous cell carcinoma were more likely to be users of methotrexate compared with cancer-free psoriasis controls. However, when the use of other immunosuppressive drugs was taken into account, use of methotrexate was no longer linked to an increased risk of squamous cell carcinoma.

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