(HealthDay News) – The long-term risk of squamous cell carcinoma (SCC) is significantly increased for patients with severe psoriasis who receive more than 350 psoralen and ultraviolet A (PUVA) treatments compared with those who receive fewer than 50 treatments, according to research published in the April issue of the Journal of the American Academy of Dermatology.
To investigate the association between PUVA exposure and SCC and basal cell carcinoma (BCC) risk, Robert S. Stern, MD, of Harvard Medical School in Boston, on behalf of the PUVA Follow-up Study, used data from 1,380 patients with severe psoriasis enrolled in a prospective cohort study who were treated with PUVA.
The researchers found that, from 1975 to 2005, 25% of study participants developed 2,973 biopsy-proven SCCs and 24% developed 1,729 BCCs. The risk of developing one or more SCC in a year correlated strongly with the total number of PUVA treatments, after adjustment for confounders (350 to 450 vs. <50 treatments, incidence rate ratio [IRR], 6.01). The risk was considerably higher when all tumors were included (IRR, 20.92). The risks for BCC were much lower (person counts IRR, 3.09; tumor counts IRR, 2.12).
“Exposure to more than 350 PUVA treatments greatly increases the risk of SCC,” the authors write. “The risks of SCC in long-term PUVA-treated patients should be considered in determining the risk of this therapy relative to other treatments for severe psoriasis.”