MINIMIZING THE RISKS OF PUVA TREATMENT

Psoralen photochemotherapy (PUVA) is a combination of orally administe red psoralen and long wave ultraviolet-A radiation (UVA), and is one o f the most effective forms of therapy for psoriasis. The unwanted effe cts of PUVA therapy can be divided into short and long term adverse ef fects. The short term adverse effects include erythema, pruritus, naus ea and headache. While short term adverse effects are limited and reve rsible after discontinuation of treatment, potential long term adverse effects such as chronic actinic skin damage, dyskeratotic and precanc erous skin conditions, nonmelanoma skin cancer, immunological alterati ons and cataract formation are of greater concern. Long term risks ass ociated with PUVA therapy can be minimised by several measures. Carefu l patient selection is mandatory; for example, patients with chronic a ctinic damage and a history of skin cancer may bear a higher risk for the development of new cancers, and previous arsenic intake and ionisi ng radiation also increase the risk of nonmelanoma skin cancers. Certa in drug combinations make it possible to lower the UVA dose, which is important because of the dose-dependent increase in the incidence of s quamous cell carcinomas in patients treated with PUVA. It has been dem onstrated that 200 treatments or a total UVA dose of 1200 J/cm2 seems to be the threshold for development of nonmelanoma skin cancer. Shield ing male genitalia during PUVA treatment is essential because of the i ncreased risk of genital squamous cell carcinomas. Yearly dermatologic al examination to detect skin cancer at an early stage is highly advis able. Sunscreen use, protective clothing and avoidance of sun exposure reduce the uncontrolled dose of solar UV radiation. Other psoralens w ith a less carcinogenic potential can be used. UVA-opaque sunglasses d uring the entire period of increased photosensitivity after psoralen i ngestion help avoid cataract formation.Assignment to PUVA ought to be based on the risk-benefit ratio for the individual patient and should be limited to those who can be monitored and controlled by informed, c ompetent and conscientious physicians.