摘要Background Recent studies suggest that circulating DNA may be a potential tumor marker for lung cancer, but most of these studies are conducted between healthy controls and lung cancer patients, with few or no benign lung disease patients included. The objective of this study was to evaluate the performance of plasma DNA quantification in discriminating lung cancer from the healthy and benign lung disease.Results Plasma DNA values were significantly increased in lung cancer patients, especially in those with metastases, and in benign lung disease patients compared with that in the healthy individuals (P＜0.001, respectively). The values in lung cancer patients were significantly increased compared with that in the benign lung disease patients (P＜0.001). The area under the curve was 0.96 [95% confidence interval (CI) 0.92-0.99] for the healthy versus lung cancer, 0.73 (95% CI 0.64-0.83) for lung cancer versus benign lung disease, and 0.86 (95% CI 0.80-0.91) for lung cancer versus the healthy and benign lung disease.Conclusions Plasma DNA quantification has a strong power to discriminate lung cancer from the healthy and from the healthy and benign lung disease, less power to discriminate lung cancer from benign lung disease. Plasma DNA quantification may be useful as a screening tool for lung cancer.