Basal cell carcinoma patients have higher UVC-mediated DNA repair incisions and lower DNA repair activity

Psoriasis is a skin disease characterized by high proliferation rate of epi dermal keratinocytes. The treatment of psoriasis includes several DNA damag ing agents, and this has caused concern that psoriasis patients are at risk of developing basal cell carcinoma (BCC). We have investigated the DNA rep air incision rate following WC irradiation by the comet assay in isolated l ymphocytes in a case-control study comprising psoriasis patients with and w ithout BCC and non-cancer patients with and without psoriasis. Previously, we have found that lymphocytes from psoriasis patients with BCC had a high rate of incisions following WC irradiation. Here we report that the lymphoc ytes from BCC patients also had the highest level of UVC-mediated DNA repai r incisions in blood samples taken two years later. We have reported earlie r that lymphocytes from psoriasis patients with BCC had the lowest level of DNA repair activity, determined by unscheduled DNA synthesis and host cell reactivation. This suggests that the DNA repair-defect in BCC patients can be distinguished by high UVC incision rate and low DNA repair activity.