The risk of skin cancer in psoriasis patients treated with UVB therapy.

Phototherapy is an effective and widely used treatment for generalised plaque psoriasis. Despite the mutagenic effects of UVB this type of therapy is still assumed to be a safe treatment option. We have performed a cross sectional study to assess the risk of skin cancer in the cohort of psoriasis patients treated with UVB. A total of 162 white patients (116 men and 46 women, mean ± standard deviation age 56.0 ± 13.5 years) were included in the study. All patients have previously been treated with UVB at least 100 times in the last 5 years. Eight patients (4.9%, 0.95 CI: 2.2-9.5%) out of the 162 included in the study had histopathologically verified skin cancer. We found that the risk of skin cancer in psoriasis patients treated with UVB correlated with the number of treatments (controlling for age) but not with the type of UVB lamp. How-ever, the overall risk of malignancy in the UVB-treated patients was not greater than in the general population.