Urinary thymine dimers and 8-oxo-2 '-deoxyguanosine in psoriasis

Psoralen in conjunction with UVA (PUVA) is perhaps the most effective treat ment for psoriasis, It is, however, a risk factor for skin cancer in these patients and there is a need to develop non-invasive assays reflective of t reatment-induced DNA damage. We report here the assessment of two important lesions, thymine dimer (T[]T) and 8-oxo-2'-deoxyguanosine (8-OHdG), in the urine of psoriasis patients. It was found that, once corrected for urine c oncentration, the psoriatic group had significantly higher (P < 0.0001) uri nary levels of thymine dimers compared to the control group. No significant differences in urinary 8-OHdG levels were noted between the psoriatic, ato pic dermatitis and control groups. Therefore biomonitoring of therapy from the very start with this simple and non-invasive assay could perhaps be an effective measure of the risk involved with the treatment allowing optimiza tion for minimal-risk therapy. (C) 1999 Federation of European Biochemical Societies.