(HealthDay News) – The long-term risk of squamous cell carcinoma (SCC) is significantly increased for patients with severe psoriasis who receive >350 psoralen and ultraviolet A (PUVA) treatments compared with those who receive <50 treatments.
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 (350–450 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.”