Clinicopathological and prognostic significance of circulating tumor cells in patients with esophageal cancer: a meta-analysis

BACKGROUND: The aim of this meta-analysis was to assess the clinicopathological and prognostic significance of circulating tumor cells (CTCs) in patients with esophageal cancer (EC). METHODS: We searched PubMed, EMBASE, Science Citation Index Expanded, Cochrane library (from inception to July 2018) with the keywords “esophageal cancer”, “circulating tumor cells”, “prognosis”, and “peripheral blood”. HR, risk ratio (RR), OR, and their 95% CIs were set as effect measures. All analyses were performed by STATA 12.0. RESULTS: Eighteen studies were retrieved; CTC-positive patients were significantly associated with poor progression-free survival (PFS) (HR=2.61; 95% CI=2.08–3.28) and overall survival (OS) (HR=2.50; 95% CI=2.12–2.94). CTC-positive patients were also associated with high recurrence (OR=2.84; 95% CI=1.81–4.44) and poor response of chemoradiotherapy (RR=0.64; 95% CI=0.43–0.96). For clinicopathological characteristics, CTC-positive patients were significantly associated with TNM staging, depth of infiltration, regional lymph nodes metastasis, distant metastasis, lymphatic invasion, and venous invasion. CONCLUSION: The meta-analysis has confirmed the significant clinicopathological and prognostic value of CTC-positive patients for both PFS and OS in patients with EC.