The development of a liquid biopsy for head and neck cancers

• CTCs and ctDNA are readily detectable in HNSCC patients.
• ctDNA enables specific complementary information for diagnosis, prognosis and management of treatment.
• Serial sampling prior to surgery, as well as post-treatment, may reveal patients at risk of relapse.
• Heterogeneity can be explored and the implications of this better understood.
• With decreasing cost of next-generation sequencing, the technology brings a new alternative for unbiased ctDNA exploration.

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.