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October 1992

Comparison of the Carcinogenic Potential of Trioxsalen Bath PUVA and Oral Methoxsalen PUVAA Preliminary Report

Author Affiliations

From the Departments of Dermatology, Karolinska Hospital, Stockholm, Sweden, University Hospital, Lund, Sweden, and University Hospital, Uppsala, Sweden.

Arch Dermatol. 1992;128(10):1341-1344. doi:10.1001/archderm.1992.01680200051005

• Background and Design.—  There is an increasing concern about the long-term carcinogenic effect of oral psoralen with long-wave UV radiation in the A range (PUVA). Most follow-up investigations indicate a definite risk of squamous cell carcinoma of the skin with long-term PUVA treatment. In a recently published study of 4799 Swedish patients who had received PUVA, it was noted that 833 patients who had received trioxsalen bath or oral trioxsalen did not show any increased risk of skin cancer in contrast to oral methoxsalen. This finding has been further investigated in this study. We compared four dermatologic university clinics in Sweden with regard to the carcinogenic potential of the PUVA regimen used. One clinic used trioxsalen bath PUVA exclusively and the other three used oral methoxsalen. Information on their PUVA-treated patients was collected and linked with information from the Swedish Cancer Registry to identify individuals with squamous cell carcinoma of the skin.

Results.—  A total of 18 squamous cell carcinomas of the skin were reported in 2975 PUVA-treated patients until 1987. The expected number was 3.1. The center using bath PUVA only had no increased risk of squamous cell carcinoma of the skin in contrast to the three centers using oral methoxsalen-PUVA. The increased risk for male subjects from those centers varied from six to 13 times that in the general population, but for female subjects a significant increased relative risk was found only at one center.

Conclusion.—  In this preliminary report, PUVA treatment with trioxsalen bath seems to be less carcinogenic than the oral dosage. However, differences in the patient populations might also have affected the outcome of the study. More information on this field is needed.(Arch Dermatol. 1992;128:1341-1344)