Malignant Melanoma in Patients Treated for Psoriasis
Severe psoriasis is effectively treated with psoralen and PUVA. It has been previously demonstrated, however, that this therapy is not without risk, including increased likelihood of squamous-cell carcinoma of the skin. Stern et al report on a prospective study that was begun in 1975 to assess the long-term risks of skin cancer subsequent to PUVA.
The study prospectively evaluates 1380 patients who began PUVA treatment for psoriasis at 16 university centers in 1975-1976. Beginning in 1991, an increased incidence of melanoma was noted. At the same time, it was observed that there was a clustering of cases in patients who had received more than 280 PUVA treatments.
Overall, by 1996, the relative risk of melanoma for persons enrolled in the study was 2.3 compared to the general population. Additionally, by the beginning of the 15-year follow-up, the relative risk was 5.4, increasing to 8.9 if the patient had received more than 250 PUVA treatments.
The authors conclude that beginning about 15 years after treatment with PUVA there is a substantial increased relative risk of melanoma. Although higher numbers of treatments (> 250) were associated with worst risk, the absolute level at which risk increases is unknown. It is recommended that persons who have received PUVA treatment be followed carefully for development of melanoma, as well as other nonmelanoma skin cancer.
Stern R, et al. N Engl J Med 1997;336: 1041-1045.