Real-time PCR quantification of plasma DNA in non-small cell lung cancer patients and healthy controls

INTRODUCTION Free-circulating DNA is present in minute amounts in plasma of healthy individuals, whereas increased levels are found in a number of malignant pathologies including non-small cell lung cancer (NSCLC). The objective of this research was the evaluation of the plasma DNA quantification capacity to distinguish between healthy subjects and non-small cell lung cancer (NSCLC) patients. MATERIAL AND METHODS Plasma samples were collected prospectively from 16 healthy volunteers and 30 untreated NSCLC patients (I-IIIA). Subsequently, free-circulating DNA extraction and quantitative real-time PCR analysis were performed. RESULTS The values of plasma DNA concentration ranged from 0.9 up to 7.0 ng/ml in healthy individuals and from 1.5 up to 50 ng/ml in NSCLC patients before treatment. Cancer group showed several-fold higher mean free-circulating DNA concentration than that present in healthy subjects (mean 12.00 vs. 2.65 ng/ml; P<0.001). A greater variability of plasma DNA concentrations was observed in NSCLC patients than in controls (SD 14.50 vs. 2.02, respectively). The area under the ROC curve was 0.87 (95% CI, 0.744 to 0.954, P<0.001). CONCLUSION Non-small cell lung cancer is associated with elevated levels of cell-free DNA in plasma with respect to healthy controls. Real-time PCR method proved its utility in effective free-circulating DNA detection and quantification.