Changes of Circulating Endothelial Cells and Microparticles after Conventional Chemotherapy in Patients with Extensive Small-Cell Lung Cancer: Relevance to Prognosis and Treatment Response

Objectives: Tumor angiogenesis is controlled by inhibitors and angiogenic factors. However, circulating endothelial cells (CECs) and microparticles (MPs) may be related to tumor angiogenesis in malignant tumors. We therefore investigated the significance of CECs and MPs variation for the prediction of treatment efficacy andprognosis in patients with extensive small-cell lung cancer (SCLC). Materials and methods: Isolation and quantification of CECs from the whole-blood was performed using immune magnetic separation (IMS) technique, while flow cytometry measurement (FCM) was used for enumerating MPs in plasma samples.Results: Twenty-six patients were included in this prospective study. The relative change in CEC and MP counts after treatment, correctly identified treatment response in 22/26 patients (84.6%) and 17/23 patients (73.9%) respectively. The difference in themedian duration of time to progression (TTP) between patient with high relative changes and those with low relative changes in CEC and MP values was not statistically significant (p=0.39 and p=0.2, respectively). By contrast, the increase in CEC and MP levels after chemotherapy tended to be inversely correlated with longer TTP duration (r²=0.111 and r²=0.171, respectively). However, onlym decreased MP values after chemotherapy have the trend to be correlated with longer TTP duration (r²=0.167).Conclusion: The relative change in CEC and MP values after treatment seems to be a useful biomarker for the evaluation of treatment response in patients with extensive SCLC. Moreover, this relative change in both biomarkers might be considered as a prognostic tool in SCLC.