Incidence of skin cancer in Japanese psoriatic patients treated with either methoxsalen phototherapy, Goeckerman regimen, or both therapies. A 10-year follow-up study.

To determine the long-term cutaneous side effects of methoxsalen phototherapy (PUVA) and Goeckerman regimen, a total of 151 Japanese psoriatic patients treated with PUVA, Goeckerman regimen, or both therapies in our department from 1976 to 1986 were evaluated for skin cancers. Sixty-seven patients had been treated with PUVA, 43 with Goeckerman regimen, and 41 with both therapies. One patient alone (62-year-old man) developed squamous cell carcinoma on the leg with cumulative ultraviolet A (UVA) dose of only 51 joules/cm2, he had a history of treatment with superficial x-ray therapy to this area 30 years prior to PUVA. The cancer was detected after 1.4 years of PUVA treatment. However, other patients at follow-up, even those who had received a cumulative dose of UVA of more than 1000 joules/cm2, had no skin cancer after more than 2 years. This report in Japanese patients confirms that only previous exposure to other risk factors such as ionizing radiation appears to be a most important factor for skin cancer formation in PUVA-treated Japanese patients.