Prognostic value of circulating endothelial cells in non-small cell lung cancer patients: a systematic review and meta-analysis

Yafang Liu, Dongmei Yuan, Wei Ye, Tangfeng Lv, Yong Song


Background: Circulating endothelial cells (CECs) have been indicated as a potential biomarker of vascular damage in a variety of cancers. Several studies have revealed CECs may reflect the extent of tumor angiogenesis; however, the role of CECs in the prognosis of non-small cell lung cancer (NSCLC) is undetermined to date. A meta-analysis has been prepared to determine whether the base level of CECs and the changes of CECs after therapy (∆CECs: post-therapeutic value minus the pre- therapeutic value) could be considered as a prognostic tool for patients with NSCLC.
Methods: Systematic reviews of studies published before April 30 2015 were conducted on the association between the levels of CECs or ∆CECs and the prognosis of NSCLC in several data bases. Hazard ratios (HRs) and the 95% confidence intervals (CIs) were used to collate the data. Similarly, heterogeneity and publication bias were also evaluated.
Results: A total of nine studies, containing eight prospective studies and one retrospective study, involving 515 patients was identified. Patients with higher level of CECs counts at baseline were associated with longer progression-free survival (PFS) (HR 0.71, 95% CI: 0.529-0.891). ∆CECs could also be considered a prognostic indicator in NSCLC patients (HR 0.575, 95% CI: 0.401-0.75). The former and the later are without a significant heterogeneity in the data (I2=21.2% and 0.0%, P=0.274 and 0.870, respectively). However, there was no correlation between the base level of CECs and the overall survival (OS) (HR 0.914, 95% CI: 0.560-1.267, I2=43.6%, P=0.150).
Conclusions: Higher levels of CECs counts at baseline and the ensuing decrease after therapy demonstrated a positive correlation with longer PFS in NSCLC patients. But this phenomenon has not been found in OS. From a certain perspective, CECs counts and ∆CECs could be potential prognostic indicators for NSCLC patients.