RISK OF CUTANEOUS CARCINOMA IN PATIENTS TREATED WITH ORAL METHOXSALEN PHOTOCHEMOTHERAPY FOR PSORIASIS

A 2.1-year prospective study of 1373 patients given oral 8-methoxypsoralen photochemotherapy for psoriasis revealed 30 patients with a total of 48 basal-cell and squamous-cell carcinomas. The observed incidence of cutaneous carcinoma was 2.63 (95 per cent confidence limits = 1.91 to 3.90) times that expected for an age, sex and geographically matched population. Relative risk to patients with history of ionizing radiation was 3.68 (99 per cent confidence limits, 2.42 to 8.69). Patients with a previous cutaneous carcinoma had a relative risk of 10.22 (99 per cent confidence limits, 4.78 to 37.08). A higher than expected proportion of squamous-cell carcinomas and an excess of squamous-cell carcinomas in areas not exposed to sun were seen. New patients with known histories of ionizing-radiation exposure or of skin tumors should be given 8-methyoxypsoralen photochemotherapy only if they understand the risks and have disabling psoriasis untreatable by other means. (N Engl J Med 300:809–813, 1979) PSORIASIS is a common disease, often disfiguring and disabling. In 1974, an effective treatment for psoriasis, orally administered 8-methoxy-psoralen and long-wave ultraviolet radiation (320 to 440 nm, UVA), known as PUVA, was reported.1 2 3 4 5 6 Although PUVA is an investigational therapy, an estimated 35,000 Americans received this treatment in 1978. Sixteen American centers collaborated in a short-term study of PUVA for psoriasis and are now participating in a five-year follow-up study evaluating the long-term safety and efficacy of this treatment, as opposed to its known short-term safety. Among the most important potential risks of PUVA is the acceleration of ultraviolet-induced skin changes,. © 1979, Massachusetts Medical Society. All rights reserved.