Changes in oxidative stress in patients screened for skin cancer after solid-organ transplantation

Transplant recipients are at high risk of nonmelanoma skin cancer (NMSC). Ultraviolet radiation can generate oxygen free radicals (OFRs), leading to oxidative stress and carcino-genesis, primarily during immunosuppression therapy. In the present study, changes in oxidative stress were examined in transplant recipients with and without NMSC. The study included 116 white adults who had undergone kidney or combined kidney-pancreas transplantation. Dermatologic follow-up revealed 16 NMSCs (13.8%). To monitor oxidative stress, peripheral blood samples were used to measure malondialdehyde (MDA), reduced glutathione, sulfhydryl (-SH) groups, OFRs, and activity of myeloperoxidase, superoxide dismutase, and catalase. The mean (SD) plasma MDA concentration was significantly greater in patients without NMSC compared with healthy control individuals (0.48 ± 0.05 nmol/mL; P < .05), whereas MDA concentration in hemolysate was slightly increased. In peripheral blood samples, the MDA concentration in both plasma (0.71 ± 0.03 nmol/mL) and hemolysate (87.74 ± 1.25 nmol/mL) was significantly increased in the NMSC group compared with the healthy control group (0.24 ± 0.05 nmol/mL vs 75.87 ± 2.8 nmol/mL; P < .05) or patients without NMSC (0.48 ± 0.04 nmol/mL vs 79.62 ± 2.77 nmol/mL; P < .05). The reduced glutathione concentration was significantly decreased in the -SH groups compared with the healthy control group (P < .05). Antioxidant activity of myeloperoxidase (0.78 ± 0.05 IU/mL) and catalase (1855.8 ± 45.41 IU/mL) was significantly increased in the group without NMSC compared with the healthy control group (0.41 ± 0.1 IU/mL vs 1642.07 ± 82.96 IU/mL) and the NMSC group (0.93 ± 0.03 IU/mL vs 2180.5 ± 15.03 IU/mL). The superoxide dismutase activity was decreased slightly but not significantly. Total production of OFRs was significantly greater in the NMSC group compared with the non-NMSC group or the healthy control group (P < .05). These findings suggest that an imbalance exists between pro-oxidant and antioxidant status in transplant recipients, with a significant difference in patients with vs without NMSC.