Stern's report, “Lymphoma Risk in Psoriasis: Results of the PUVA Follow-up Study,”1 is extremely interesting and beckons us to question “Why?” and “Should we be doing anything differently for our patients being treated with methotrexate?” Stern examined the cohort of 1380 patients initially treated with psoralen–UV-A from 1975 through 1976 and found that the incidence of lymphoma was increased in the subgroup of patients who had been exposed to high levels of methotrexate (incidence rate ratio, 4.39; 95% confidence interval, 1.59-12.06).
Whitmore SE. Methotrexate and Risk for Lymphoma. Arch Dermatol. 2007;143(5):659-675. doi:10.1001/archderm.143.5.663-b