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

Background: The prognostic significance of circulating tumor cells in patients with lung cancer is controversial. Therefore, we aimed to comprehensively and quantitatively assess the prognostic role of CTCs in patients with lung cancer. Methods: The relevant literature was searched using PubMed, the Cochrane database and the China National Knowledge Internet database (up to June 2016). Using Review Manager 5.1.2, a meta-analysis was performed using hazard ratio (HR), odds ratio (OR) and 95% confidence interval (CI) as effect values. Results: Thirty studies comprising 2,060 patients with lung cancer were analyzed. The pooled HR values showed that circulating tumor cells were significantly correlated with overall survival (HR = 2.63, 95% CI [2.04, 3.39]) and progression-free survival (HR = 3.74, 95% CI [2.49, 5.61]) in these patients. Further subgroup analyses were conducted and categorized by sampling time, detection method, and histological type; these analyses showed the same trend. The pooled OR values showed that circulating tumor cells were associated with non small cell lung cancer stage(OR = 2.11, 95% CI [1.42, 3.14]), small cell lung cancer stage (OR = 10.91, 95% CI [4.10, 29.06]), distant metastasis (OR = 7.06, 95% CI [2.82, 17.66]), lymph node metastasis (OR = 2.31, 95% CI [1.19,4.46]), and performance status(OR = 0.42, 95% CI [0.22, 0.78]). Conclusion: The detection of circulating tumor cells in the peripheral blood of patients with lung cancer can be indicative of a poor prognosis.