Nationwide case-control study of use of methotrexate and risk of skin cancer in Denmark

A nationwide Danish case-control study included patients with basal cell carcinoma (BCC), cutaneous cell carcinoma (cSCC), and cutaneous malignant melanoma (CMM) and 10 controls matched to each case on sex and birth year. Use of a cumulated dose ≥ 2,5 g of methotrexate was associated with increased risk of BCC (aOR 1.29; 95% CI 1.20-1.38), cSCC (1.61; 1.37-1.89), and CMM (1.35; 1.13-1.61). For BCC and cSCC, ORs increased with higher cumulative doses. These associations were not consistent when restricting the study population to patients with psoriasis.