Circulating tumor cells as biomarkers in head and neck cancer: recent advances and future outlook.

INTRODUCTION: Assessment of circulating tumor cells (CTCs) in peripheral blood from solid cancer patients including head and neck squamous cell carcinoma (HNSCC) has proven useful for detection of subclinical disease that otherwise remains invisible for current staging techniques. Based on large cohort studies, diagnostic tests for enumeration of CTCs have been developed, which can be used for tumor staging, prognosis, treatment monitoring, and post-treatment surveillance. Areas covered: Here, we briefly summarize the history of CTC discovery. We review the current evidence of a diagnostic potential of CTCs in HNSCC. We present recent technical advancements in the tools for enrichment, detection, and molecular characterization of CTCs. We also discuss potential clinical applications of CTC detection for personalized treatment strategies. Expert commentary: Recent technical advances in the platforms for enrichment, detection, and comprehensive molecular characterization of CTC represent a great opportunity to improve our understanding in the biology of CTCs and will allow to expand the clinical utility of CTCs in HNSCC. Especially, HNSCC patients with recurrent/metastatic disease associated dismal prognosis and little improvement in treatment outcome over the past decade might benefit in the future from incorporation of CTC assays in clinical management.