{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,25]],"date-time":"2026-08-25T04:28:08Z","timestamp":1787632088374,"version":"build-2736575974"},"reference-count":33,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2026,8,22]],"date-time":"2026-08-22T00:00:00Z","timestamp":1787356800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100004271","name":"Sapienza University of Rome","doi-asserted-by":"crossref","award":["RG124190BFEDC02A"],"award-info":[{"award-number":["RG124190BFEDC02A"]}],"id":[{"id":"10.13039\/501100004271","id-type":"DOI","asserted-by":"crossref"}]},{"award":["RG124190BFEDC02A"],"award-info":[{"award-number":["RG124190BFEDC02A"]}],"id":[{"id":"https:\/\/ror.org\/02be6w209","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Curr. Issues Mol. Biol.","CIMB"],"abstract":"<jats:p>Liquid biopsy, the analysis of tumor-derived material in blood, saliva, and other body fluids, is increasingly explored for the diagnosis, surveillance, and molecular characterization of head and neck squamous cell carcinoma (HNSCC). Its performance, however, is not uniform across the disease, and the reason is fundamentally molecular. human papillomavirus (HPV)-positive oropharyngeal cancers carry viral oncogenes that are absent from the host genome and therefore provide a near ideal, tumor specific circulating marker, whereas HPV-negative tumors are driven by a heterogeneous somatic landscape that offers no single universal target. In this narrative review, we adopt a molecular perspective. We first examine the biological origin of circulating tumor DNA and of the other analytes that liquid biopsy can interrogate including circulating tumor HPV DNA, viral transcripts, microRNAs, extracellular vesicles, and methylation signatures. We then consider how analytical platforms, from droplet digital PCR to next generation and ultrasensitive whole-genome sequencing, translate these molecules into measurements. Only afterward do we discuss the clinical questions, organized by clinical objective rather than by individual study: diagnosis and early detection, prognosis and risk stratification, treatment response monitoring, minimal residual disease and surveillance, and biomarker guided de-escalation in HPV-positive disease. Twelve registered clinical trials, involving approximately 1183 patients, are presented as illustrations of these questions. We close on the biological and technical gaps that still separate promising signals from clinical practice, and on the multi analyte and dynamic strategies most likely to bridge them. At present, liquid biopsy should be regarded as a complementary tool rather than as a replacement for established clinicopathological assessment.<\/jats:p>","DOI":"10.3390\/cimb48090853","type":"journal-article","created":{"date-parts":[[2026,8,24]],"date-time":"2026-08-24T13:20:43Z","timestamp":1787577643000},"page":"853","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Liquid Biopsy in Head and Neck Squamous Cell Carcinoma: A Molecular Perspective on Circulating Biomarkers and Their Clinical Translation"],"prefix":"10.3390","volume":"48","author":[{"ORCID":"https:\/\/orcid.org\/0009-0004-2200-9636","authenticated-orcid":false,"given":"Francesca","family":"Cascone","sequence":"first","affiliation":[{"name":"Division of Otolaryngology-Head and Neck Surgery, Ospedale San Camillo de Lellis, ASL Rieti-Sapienza University, Viale Kennedy, 02100 Rieti, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2696-1048","authenticated-orcid":false,"given":"Gabriele","family":"Riccardi","sequence":"additional","affiliation":[{"name":"Division of Otolaryngology-Head and Neck Surgery, Ospedale San Camillo de Lellis, ASL Rieti-Sapienza University, Viale Kennedy, 02100 Rieti, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1488-8392","authenticated-orcid":false,"given":"Dario","family":"Benelli","sequence":"additional","affiliation":[{"name":"Department of Molecular Medicine, Sapienza University of Roma, Viale Regina Elena 324, 00161 Roma, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Riccardo","family":"Maurizi","sequence":"additional","affiliation":[{"name":"Division of Otolaryngology-Head and Neck Surgery, Ospedale San Camillo de Lellis, ASL Rieti-Sapienza University, Viale Kennedy, 02100 Rieti, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-8984-8188","authenticated-orcid":false,"given":"Camilla","family":"Laureti","sequence":"additional","affiliation":[{"name":"Division of Otolaryngology-Head and Neck Surgery, Ospedale San Camillo de Lellis, ASL Rieti-Sapienza University, Viale Kennedy, 02100 Rieti, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0651-1816","authenticated-orcid":false,"given":"Carla","family":"Petrella","sequence":"additional","affiliation":[{"name":"Institute of Biochemistry and Cell Biology (IBBC), National Research Council (CNR), Viale del Policlinico 155, 00161 Roma, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Carlo","family":"Cogoni","sequence":"additional","affiliation":[{"name":"Department of Molecular Medicine, Sapienza University of Roma, Viale Regina Elena 324, 00161 Roma, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Antonio","family":"Minni","sequence":"additional","affiliation":[{"name":"Division of Otolaryngology-Head and Neck Surgery, Ospedale San Camillo de Lellis, ASL Rieti-Sapienza University, Viale Kennedy, 02100 Rieti, Italy"},{"name":"Interdisciplinary Department of Well-Being, Health and Environmental Sustainability (BeSSA), Sapienza University of Roma Via delle Fontanelle, 02100 Rieti, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1737-9064","authenticated-orcid":false,"given":"Christian","family":"Barbato","sequence":"additional","affiliation":[{"name":"Institute of Biochemistry and Cell Biology (IBBC), National Research Council (CNR), Viale del Policlinico 155, 00161 Roma, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,22]]},"reference":[{"key":"ref_1","first-page":"209","article-title":"Global cancer statistics 2020: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries","volume":"71","author":"Sung","year":"2021","journal-title":"CA Cancer J. 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