Published online Feb 21, 2017. doi: 10.3748/wjg.v23.i7.1310
Peer-review started: December 21, 2016
First decision: January 10, 2017
Revised: January 20, 2017
Accepted: February 7, 2017
Article in press: February 8, 2017
Published online: February 21, 2017
To perform a meta-analysis of the related studies to assess whether circulating tumor cells (CTCs) can be used as a prognostic marker of esophageal cancer.
PubMed, Embase, Cochrane Library and references in relevant studies were searched to assess the prognostic relevance of CTCs in patients with esophageal cancer. The primary outcome assessed was overall survival (OS). The meta-analysis was performed using the random effects model, with hazard ratio (HR), risk ratio (RR) and 95% confidence intervals (95%CIs) as effect measures.
Nine eligible studies were included involving a total of 911 esophageal cancer patients. Overall analyses revealed that CTCs-positivity predicted disease progression (HR = 2.77, 95%CI: 1.75-4.40, P < 0.0001) and reduced OS (HR = 2.67, 95%CI: 1.99-3.58, P < 0.00001). Further subgroup analyses demonstrated that CTCs-positive patients also had poor OS in different subsets. Moreover, CTCs-positivity was also significantly associated with TNM stage (RR = 1.48, 95%CI: 1.07-2.06, P = 0.02) and T stage (RR = 1.44, 95%CI: 1.13-1.84, P = 0.003) in esophageal cancer.
Detection of CTCs at baseline indicates poor prognosis in patients with esophageal cancer. However, this finding relies on data from observational studies and is potentially subject to selection bias. Prospective trials are warranted.
Core tip: The clinical validity of circulating tumor cells (CTCs) is still controversial and inconclusive in patients with esophageal cancer. Our meta-analysis provides strong evidence that detection of CTCs in peripheral blood at baseline is an independent prognosticator of poor survival outcomes in esophageal cancer patients.