Although methotrexate has been associated with an increased risk for cutaneous malignant melanoma in patients with rheumatoid arthritis, a study has found no association between methotrexate treatment and risk for this form of melanoma in patients with psoriasis. The findings, published in the British Journal of Dermatology, may be reassuring for dermatologists who prescribe methotrexate to patients with psoriasis.

The nested case-control study included a register data comprising Swedish patients with psoriasis and a first case of cutaneous malignant melanoma between 2010 and 2016 (N=395). A total of 10 randomly selected patients with psoriasis and without cancer were matched to each case of cutaneous malignant melanoma in terms of age and sex.

Study investigators examined the accumulated doses of methotrexate in both the cutaneous malignant melanoma cases and control groups. Stages of cutaneous malignant melanoma were compared in cases who were and were not exposed to methotrexate. In addition, mortality and melanoma-specific mortality were compared in the 2 groups and within the cutaneous malignant melanoma cases.

Approximately 25% of patients with cutaneous malignant melanoma and 24% of control patients without cutaneous malignant melanoma had filled any prescription of methotrexate (univariate conditional logistic regression model of ever-exposure of methotrexate, odds ratio, 1.0; 95% CI, 0.8-1.3; P =.86). There was no difference between cases and control patients in regard to survival (adjusted hazard ratio [aHR], 1.4; 95% CI, 1.0-2.1; P =.058). Within the cutaneous malignant melanoma case group, there also were no differences between patients who were and were not exposed to methotrexate in terms of mortality (aHR, 0.7; 95% CI, 0.2-1.9; P =.44) and melanoma-specific mortality (aHR, 0.8; 95% CI, 0.2-3.6; P =.76).


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Study limitations include the lack of data on common risk factors of cutaneous malignant melanoma, the inclusion of only patients from Sweden, and the lack of data on the number of phototherapy treatments initiated in this study population.

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The study investigators suggest that their findings are reassuring for dermatologists, especially “since methotrexate still constitutes an important drug in the dermatology treatment armamentarium.”

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Reference

Polesie S, Gillstedt M, Paoli J, Osmancevic A. Methotrexate treatment for psoriasis patients and risk of cutaneous melanoma: a nested case-control study [published online January 25, 2020]. Br J Dermatol. doi: 10.1111/bjd.18887