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

Background: Many studies have assessed the clinical use of circulating tumor cells (CTCs) in head and neck cancer, but the clinicopathological and prognostic significance of CTCs is still unclear. Materials and methods: Two authors systematically searched the studies independently with keywords in PubMed, MEDLINE, EMBASE, Science Citation Index Expanded and Cochrane Library (from inception to February 2017). The estimated hazard ratio (HR), risk ratio (RR) and their 95% confidence intervals (95% CIs) were set as effect measures. All analyses were performed by STATA 12.0. Results: A total of 17 studies were included in this meta-analysis. Positive CTCs were significantly associated with poor overall survival (HR = 2.80, 95% CI: 1.34-5.86), disease-free survival (HR = 3.86, 95% CI: 2.03-7.36) and progression-free survival (HR = 3.31, 95% CI: 1.71-6.42). CTC-positive patients tend to have higher recurrence (RR = 2.13, 95% CI: 1.26-3.59) and regional lymph node metastasis (RR = 1.18, 95% CI: 1.02-1.36) rate and a more advanced tumor stage (RR = 1.16, 95% CI: 1.03-1.32). Conclusion: Our meta-analysis has confirmed the significant prognostic value of CTCs in head and neck cancer patients. The presence of CTCs could be used as a monitoring tool for tumor status of head and neck cancer, especially for the early detection of the tumor recurrence and progression, advanced disease and the node metastasis.