Long-term PUVA Therapy Impacts Patients’ Risk for Non-melanoma Skin Cancers The results of a new study in the Journal of the American Academy of Dermatology (JAAD) reveal a great deal of information about the link between psoralen and ultraviolet A (PUVA) therapy for psoriasis and an increased risk of non-melanoma skin cancer. The findings demonstrate, among other things, a significantly increased risk for squamous cell carcinoma (SCC) that is directly impacted by the number of PUVA treatments.
Robert S. Stern, MD, of the Department of Dermatology at Beth Israel Deaconess Medical Center, Harvard Medical School, performed the study over the course of nearly 30 years (1975 to 2005). Among 1,380 psoriasis patients who were first treated with PUVA from 1975 to 1976, one-quarter of patients (351/1,380) patients developed 2973 biopsy-proven cases of SCC and 330 (24%) developed 1729 basal cell carcinomas (BCC). After adjusting for age, gender and other significant cofounders, “the risk of developing one or more SCC in a year was strongly associated with total number of PUVA treatments (350 to 450 vs <50 treatments, incidence rate ratio [IRR] = 6.01, 95% confidence interval [CI] = 4.41-8.20),” according to the results of the study in JAAD. When all tumors were included in such an analysis, the risk was significantly higher (IRR = 20.92, 95% CI = 14.08-31.08).
The corresponding risk for BCC was much lower, according to the JAAD abstract (person counts IRR = 3.09, 95% CI = 2.36-4.06; tumor counts IRR = 2.12, 95% CI = 1.47-3.05). The article acknowledges that the study was conducted solely with patients who had severe psoriasis and that “an unknown factor associated with higher dose exposure to PUVA in our cohort that was not included in our analysis could account for the observed associations.”
However, despite the limitations, the author concludes: “Exposure to more than 350 PUVA treatments greatly increases the risk of SCC. Exposure to fewer than 150 PUVA treatments has, at most, modest effects on SCC risk. Even high-dose exposure to PUVA does not greatly increase BCC risk. 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.”
