Liquid biopsy in head and neck tumors: novel approaches and clinical applications

Head and neck cancers (HNCs) represent one of the most prevalent and lethal types of cancer, accounting for 4.7% of annual cancer new cases and 4.9% of cancer-related mortalities. These high prevalence and mortality rates have positioned HNCs as a global health issue. Despite advances in disease treatment methods, the prognosis of patients with advanced or recurrent diseases remains poor. The difficulty of early-stage diagnosis of HNCs is one of the primary contributors to this reduced long-term survival. Currently available diagnostic and disease-monitoring tools, such as tissue biopsy and imaging techniques, are associated with several limitations, including invasiveness, limited repeatability, and limited sensitivity for detecting minimal residual disease (MRD) and microscopic metastases. In recent years, liquid biopsy has emerged as a promising approach, enabling minimally invasive detection of tumor-related biomarkers in body fluids. This review aims to provide a comprehensive overview of the progress and pitfalls of liquid biopsy in the context of HNCs. In this regard, we discuss the principles of liquid biopsy, applicable biomarker types, sample sources, and advanced detection methods. Furthermore, the current status of liquid biopsy in clinical trials of HNCs and the challenges of its clinical translation are also comprehensively explored.