Cancer in patients with psoriasis.

In a study of 150 non-PUVA-treated patients with psoriasis matched against a control group of patients with diabetes, the incidence of skin cancer in the psoriasis group was 1.96/yr, which was three times that of the diabetes patients. This figure is statistically significant. The prevalence of internal cancer was only half that of the patients with diabetes. This figure, however, is not significant.