Methotrexate used for psoriasis and the risk of noncutaneous or cutaneous malignancy.

Using case-control methods, we separately evaluated the risk of noncutaneous and cutaneous malignancy associated with exposure to methotrexate as it is used in the treatment of severe psoriasis. An analysis of 26 cases of noncutaneous cancer and 104 matched controls revealed no association between the development of noncutaneous malignancy and exposure to methotrexate (relative risk = 0.96; upper bound 95% confidence interval = 2.0). An analysis of 80 cases of nonmelanoma skin cancer and 297 matched controls revealed a relative risk of 1.2 for the development of cutaneous malignancy among those with exposure to methotrexate (upper bound 95% confidence interval = 1.9). Our data suggest that methotrexate, as it is used in the treatment of severe psoriasis, does not increase the risk of noncutaneous or cutaneous malignancy.