Significance of the urinary 8-OHdG level as an oxidative stress marker in lung cancer patients

Objective: In the present study, we investigated the relationship between the urinary excretion rate of the oxidized nucleoside 8-hydroxydeoxyguanosine (8-OHdG) and clinical factors in lung cancer patients. Methods: The present study included 100 patients, who underwent a lung surgery. The patients included 62 men and 38 women with a mean age of 65.5 years ranging from 35 to 82. The diagnosis included 81 primary lung cancers, 9 metastatic lung cancers and 10 benign lung diseases. Urine samples collected for 24 h were analyzed for the content of 8-OHdG using an ELISA assay. Results: The urinary excretion rate of 8-OHdG in smokers was significantly higher than that in never-smokers. Specifically, the 8-OHdG excretion rate of current smokers was higher than that of patients who had quit smoking for longer than 1 month. Excluding current smokers, the urinary excretion rate of 8-OHdG did not relate to age or gender, but to the malignant potential of the disease. The urinary 8-OHdG level increased in the order of metastatic lung cancer, primary lung cancer and benign disease. In lung cancer patients, furthermore, the mean urinary 8-OHdG level of patients with stages II-IV disease was significantly lower than that of patients with stage 1 disease. Conclusions: Smoking significantly increased the urinary excretion rate of 8-OHdG, suggesting that smoking causes an increased rate of oxidative DNA modifications. On the other hand, the capacity to repair oxidative DNA modifications might be impaired to some extent in cancer patients. (c) 2008 Published by Elsevier Ireland Ltd.