A comparison between mutational profiles in tumour tissue DNA and circulating tumour DNA in head and neck squamous cell carcinoma---A systematic review.

Head and neck cancer is the seventh most common malignancy globally. Head and neck squamous cell carcinoma (HNSCC) originates from squamous cells and 90% of HNC are HNSCC. The gold standard for diagnosing HNSCC is tissue biopsy. However, given tumour heterogeneity, biopsies may miss important cancer-associated molecular signatures, and more importantly, after the tumour is excised, there is no means of tracking response to treatment in patients. Captured under liquid biopsy, circulating tumour DNA (ctDNA), may identify in vivo molecular genotypes and complements tumour tissue analysis in cancer management. A systematic search was conducted in PubMed, Embase, Scopus and the Cochran Library between 2012 to early 2023 on ctDNA in HNSCC using publications written in English. We summarize 20 studies that compared mutational profiles between tumour tissue DNA (tDNA) and ctDNA, using a cohort of 631 HNSCC patients and 139 controls. Among these studies, the concordance rates varied greatly and the most mutated and the most concordant gene was TP53, followed by PIK3CA, CDKN2A, NOTCH1 and FAT1. Concordant variants were mainly found in Stage IV tumours, and the mutation type is mostly single nucleotide variants (SNV). We conclude that, as a biomarker for HNSCC, ctDNA demonstrates great promise as it recapitulates tumour genotypes, however additional multi-central trials are needed.