Developing non-invasive diagnostic tools in the field of head and neck oncology has been a challenge. Analysis of circulating tumour derivatives in a patient’s blood has been explored in other solid cancers. This includes analysis of circulating tumour DNA, intact circulating tumour cells (CTCs) and exosomes. These circulating tumour derivatives provide avenues of investigation which can be representative of a patient’s primary tumour signature and can be assessed from a patient’s blood sample. In advanced stage cancer patients, these tumour derivatives are found in higher amounts, attributed to higher cellular turnover (apoptosis, autophagy), lysed CTCs and sloughing from necrotic tumours. Head and neck squamous cell carcinoma (HNSCC) patients often present with advanced disease associated with a poor 5-year survival of <50%. Outside of sophisticated imaging and clinical examination, there is a lack of available biomarkers to measure disease burden, and/or response to therapy. Implementation of a liquid biopsy in HNSCC through serial blood samples has the potential to detect metastatic events earlier, thereby allowing better selection of appropriate treatment choices, predict prognosis in patients with potentially curable disease, monitor systemic therapies and residual disease post-treatment.
A proposed utility of the Liquid Biopsy: Serial sampling of plasma for monitoring of tumour-specific template, pre and post-treatment could help optimise sequence of therapy, stratify patients based on response, and allow for observation of resistance prior to overt radiologic progression.