title: Prognostic value of circulating endothelial cells in non-small cell lung cancer patients: a systematic review and meta-analysis.
abstract: 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 (I(2)=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, I(2)=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.
authors.affiliation: 1 Department of Respiratory Medicine, 2 Department of Orthopedics Medicine, Jinling Hospital, Southern Medical University, Nanjing 210002, China.
authors.forename: Yafang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: 1 Department of Respiratory Medicine, 2 Department of Orthopedics Medicine, Jinling Hospital, Southern Medical University, Nanjing 210002, China.
authors.forename: Dongmei
authors.initials: D
authors.lastname: Yuan
authors.affiliation: 1 Department of Respiratory Medicine, 2 Department of Orthopedics Medicine, Jinling Hospital, Southern Medical University, Nanjing 210002, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Ye
authors.affiliation: 1 Department of Respiratory Medicine, 2 Department of Orthopedics Medicine, Jinling Hospital, Southern Medical University, Nanjing 210002, China.
authors.forename: Tangfeng
authors.initials: T
authors.lastname: Lv
authors.affiliation: 1 Department of Respiratory Medicine, 2 Department of Orthopedics Medicine, Jinling Hospital, Southern Medical University, Nanjing 210002, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Song
keywords: Circulating endothelial cells (CECs); non-small cell lung cancer (NSCLC); prognostic; the change of circulating endothelial cells (∆CECs)