Endothelial progenitor cells are associated with response to chemotherapy in human non-small-cell lung cancer

Purpose Bone marrow-derived endothelial progenitor cells (EPCs) play an important role in angiogenesis and tumor growth. However, the clinical relevance of EPCs in non-small-cell lung cancer (NSCLC) remains unclear. Recently, some reports suggested that EPCs correlate with clinical behavior of cancer patients. We assessed the hypothesis that EPCs correlate with efficient of therapy, prognosis, and clinicopathological factors, and EPCs may offer a possible biomarker for treatment outcome in NSCLC. Methods EPCs labeled with CD34, CD133, and vascular endothelial growth factor receptor-2 (VEGFR-2) antibodies were counted by flow cytometry in the peripheral blood of 31 NSCLC patients. We categorized two groups of NSCLC patients according to circulating EPC numbers. We examined age, pathological stage, histological type, Fluoro-D-glucose Positron emission tomography (FDG-PET), response to therapy, progression-free survival, and tumor size of NSCLC patients and investigated whether these factors correlate with EPC counts. Results Circulating EPC numbers before antitumor therapy were increased in NSCLC patients compared with healthy controls (P < 0.05). In NSCLC patients, therapy was significantly effective in low circulating EPC group compared with that of high (P\ 0.05). Furthermore, the low EPC group showed significantly longer progression-free survival times than that of high (P < 0.05). However, no significant associations with age, gender, histological type, pathological stage, or FDG-PET were detected. Conclusion Peripheral blood levels of bone marrow-derived EPCs are significantly increased in patients with NSCLC and correlate with response to chemotherapy. EPCs may offer a possible biomarker for efficient of treatment and prognosis.