Long-term follow-up of skin cancer in the PUVA-48 cooperative study.

Five-hundred fifty-one psoriasis patients receiving therapy with psoralen plus UVA light in seven medical centers for up to 10 years were evaluated for the development of skin cancer. Basal cell carcinoma developed in 13 patients (2.4%), and squamous cell carcinoma (SCC) developed in 9 (1.6%), an incidence that is significantly elevated over that in the general population. The increase in basal cell carcinoma was found only in patients with exposure to other carcinogenic agents, whereas the increase in SCC was also seen in patients without such exposures. Cumulative UVA dosage was not correlated with the development of basal cell carcinoma, but there was a trend of increasing numbers of SCCs in patients with higher dosages. Five of 9 patients had SCCs on sites that were not sun exposed. All patients with tumors had them treated surgically, and, to date, none have recurred. This study confirms a previous report of an increase in the incidence of SCC in psoriatic patients treated with PUVA.