Endothelial progenitor cells as an angiogenic biomarker for the diagnosis and prognosis of lung cancer

Background: Angiogenesis is mediated by endothelial progenitor cells (EPCs) derived from bone-marrow. In this prospective study, we tried to investigate the clinical utility of circulating EPCs in lung cancer (LC) patients. Materials and methods: Flow cytometry technique was used to assess circulating EPCs according to the immuno-phenotype CD45-CD34+ CD133+CD146+ mononuclear cells. Sixty patients and 30 controls were included in this prospective study. Results: The mean of baseline EPC numbers was significantly higher in LC patients than in controls (p =0.003). Pretreatment EPC values were significantly correlated with primary tumor size (p = 0.05) and tumor response (p = 0.04). Receiver operating characteristics (ROC) curves were plotted to discriminate EPC numbers between patients and controls. Using ROC analysis, the optimal cutoff value was 125 cells/mL with a sensitivity and a specificity for baseline EPCs of 76.7% and 63.3%, respectively. According to this cutoff value, basal EPC values were significantly correlated with primary tumor size (p = 0.047) and response to chemotherapy (p = 0.034). High EPC levels were significantly associated with longer progression-free survival (PFS) and overall survival (OS) duration (p = 0.0043 and p = 0.02, respectively). Conclusion: Increased baseline EPC values seem to be a useful biomarker for the prediction of prognosis and tumor response in LC patients. Furthermore, high EPC levels at diagnosis might be an indicator of tumor growth and longer survival in LC patients.