Circulating DNA is a non-invasive prognostic factor for survival in non-small cell lung cancer

Introduction: Circulating plasma DNA is present in a considerably higher concentration in lung cancer patients than in controls. Conflicting data are reported about circulating DNA as a prognostic factor. The aim of this study was to prospectively analyse the relationship of circulating plasma DNA with overall survival (OS) of previously untreated non-small cell lung cancer (NSCLC) patients. Methods: 46 untreated NSCLC patients and 21 controls with a follow-up time of 6.5 years were analyzed. Quantification of baseline circulating plasma DNA was performed by a real-time quantitative polymerase chain reaction (qPCR) targeting the human beta-globin gene. Survival analysis was performed using the Kaplan-Meier method and compared with a Cox-regression analysis. Results: The median DNA concentration of the patients who died (87%) was significantly higher compared to the patients that survived at the end of follow-up (55 ng/ml versus 23 ng/ml, p = 0.02). In patients with higher DNA concentration overall survival was significantly worse. In this study no relation of DNA concentration with tumour characteristics, age, gender or pulmonary inflammatory conditions was found. Conclusion: In this study a high circulating plasma DNA concentration at time of diagnosis in NSCLC patients was a prognostic factor for poorer survival. Circulating DNA may be used as a non-invasive biomarker to refine the prognostic profile in NSCLC patients. (C) 2009 Elsevier Ireland Ltd. All rights reserved.