Prognostic value of circulating tumor cells in patients with squamous cell carcinoma of the head and neck: a systematic review and meta-analysis

The prognostic value of circulating tumor cells (CTCs) in patients with squamous cell carcinoma of the head and neck (SCCHN) is controversial. The objective of this study was to evaluate the prognostic value of CTCs in patients with SCCHN by conducting a meta-analysis. We systematically searched scientific literature published before June 10, 2014, using the PubMed, ScienceDirect, Cochrane Library, and EMBASE databases. Studies evaluating the correlation of CTC status with tumor-node-metastasis (TNM) disease stage, nodal involvement, and disease progression (recurrence or metastasis) in patients with SCCHN were selected for the analysis. Pooled odds ratio (OR) and 95 % confidence interval (CI) were calculated using the fixed-effects model or the random-effects model in the presence of heterogeneity. Our analysis consisted of eight studies, enrolling a total of 433 patients. The disease progression (recurrence/metastasis) rate in the CTC-positive patients was significantly higher (OR 3.44; 95 % CI 1.87-6.33; p < 0.01) compared with the patients without disease progression. However, there was no significant difference between TNM disease stage III-IV and stage I-II in the presence of CTCs (OR 1.54; 95 % CI 0.87-2.72; p > 0.05). CTC status did not correlate with nodal involvement (OR 1.20; 95 % CI 0.67-1.90; p > 0.05). This meta-analysis indicates that detection of CTCs has a predictive value in patients with SCCHN, particularly those with tumor progression. The presence of CTCs in patients with SCCHN has a poor prognosis compared with the patients without CTCs. Detection of CTCs might be served as a prognosticator in patients with SCCHN. Further studies based on homogeneous populations are warranted to confirm these findings.