Performance of oral HPV DNA, oral HPV mRNA and circulating tumor HPV DNA in the detection of HPV-related oropharyngeal cancer and cancer of unknown primary

Human papillomavirus circulating tumor DNA: a diagnostic tool in squamous cell carcinoma of unknown primary-a pilot study

Introduction

Neck mass is the most common presentation of human papillomavirus-related (HPV-related) oropharyngeal squamous cell carcinoma (OPSCC). Recently, circulating tumor HPV-DNA (ctHPVDNA) assays have been developed to detect active OPSCC. This pilot study investigates the diagnostic accuracy of ctHPVDNA in establishing HPV status for known vs. unknown OPSCC presenting as a neck mass.

Methods

A single-institution pilot study was conducted on all patients with OPSCC presenting as a neck mass between 2021 and 2022. The diagnostic accuracy of ctHPVDNA was compared to that of standard diagnostic procedures used to obtain HPV status according to the American Society of Clinical Oncology (ASCO) guideline for squamous cell carcinoma of unknown primary (SCCUP). Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of ctHPVDNA were calculated.

Results

A total of 27 patients were included; 70.4% were current or former smokers, 48.1% (N = 13) had identifiable primaries, and 51.9% (N = 14) had SCCUP. Four patients with known primaries required operative direct laryngoscopy with biopsy (DLB) to establish HPV status. Two patients with SCCUP underwent diagnostic transoral robotic surgery (TORS) to establish HPV status and localize the primary. Twelve patients underwent therapeutic TORS and neck dissection. The gold standard for HPV status was based on final histopathologic p16 or HPV in situ hybridization (ISH) staining during workup/treatment. ctHPVDNA had 95.8% sensitivity, 100% specificity, 100% PPV, and 75% NPV in predicting HPV-positive OPSCC in the whole sample. Binary logistic regression model using ctHPVDNA results to predict HPV-positive OPSCC was significant (-2 log likelihood = 5.55, χ2 = 8.70, p <.01, Nagelkerke's R squared = .67). Among patients with identifiable primaries, all patients had HPV-positive tumors on final pathology, and ctHPVDNA was positive in 100%. In the unknown primary patients, ctHPVDNA had 90.9% sensitivity, 100% specificity, 100% PPV, and 75% NPV.

Discussion

ctHPVDNA demonstrated good diagnostic accuracy for both known and unknown primaries. Incorporation of ctHPVDNA into the diagnostic algorithm for SCCUP may reduce the need for multiple procedures to establish HPV status.

[Update: Epidemiology and Prevention of Oropharyngeal Cancer]

Due to the association with the causal HPV-16 infection, the oropharyngeal carcinoma spreads into two separate entities depending on HPV-16 positivity. More recent data show a diversified picture of the importance and prevalence of the surrogate parameter p16 (discordance) for a definitive HPV-16 association, which varies worldwide. In the context of prevention options, vaccination is of major and HPV screening of healthy people only of little importance.

Prognostic and predictive biomarkers in head and neck cancer: something old, something new, something borrowed, something blue and a sixpence in your shoe

A biomarker is a measurable indicator of biological or pathological processes or the response to an exposure or intervention and is used to guide management decisions. In head and neck pathology, biomarkers are assessed by histological criteria and immunohistochemical and molecular studies. Surgical resection remains the mainstay of management of many head and neck malignancies. Adjuvant radiotherapy and/or systemic therapy may be administered depending on the presence of adverse prognostic factors identified on histopathological or immunohistochemical examination. In this review, we outline the clinically relevant prognostic and predictive factors in head and neck malignancies including conventionally recognised factors such as tumour size, depth of invasion, lymphovascular and perineural invasion and margin status as well as novel evolving factors such as recurrent genetic rearrangements and assessment of immune checkpoints. Practical issues are discussed to assist with recognising and reporting of these factors. A summary of useful tools such as structured pathology report formats is also included to assist with comprehensive reporting of all clinically relevant parameters, minimise risk and improve workflow efficiencies.

Comparing the Diagnostic Performance of Quantitative PCR, Digital Droplet PCR, and Next-Generation Sequencing Liquid Biopsies for Human Papillomavirus-Associated Cancers

Human papillomavirus (HPV)-associated cancers, including oropharyngeal squamous cell carcinoma (HPV + OPSCC), cervical cancer, and squamous cell carcinoma of the anus (HPV + SCCA), release circulating tumor HPV DNA (ctHPVDNA) into the blood. The diagnostic performance of ctHPVDNA detection depends on the approaches used and the individual assay metrics. A comparison of these approaches has not been systematically performed to inform expected performance, which in turn affects clinical interpretation. A meta-analysis was performed using Ovid MEDLINE, Embase, and Web of Science Core Collection databases to assess the diagnostic accuracy of ctHPVDNA detection across cancer anatomic sites, detection platforms, and blood components. The population included patients with HPV + OPSCC, HPV-associated cervical cancer, and HPV + SCCA with pretreatment samples analyzed by quantitative PCR (qPCR), digital droplet PCR (ddPCR), or next-generation sequencing (NGS). Thirty-six studies involving 2986 patients met the inclusion criteria. The sensitivity, specificity, and quality of each study were assessed and pooled for each analysis. The sensitivity of ctHPVDNA detection was greatest with NGS, followed by ddPCR and then qPCR when pooling all studies, whereas specificity was similar (sensitivity: ddPCR > qPCR, P < 0.001; NGS > ddPCR, P = 0.014). ctHPVDNA from OPSCC was more easily detected compared with cervical cancer and SCCA, overall (P = 0.044). In conclusion, detection platform, anatomic site of the cancer, and blood component used affects ctHPVDNA detection and must be considered when interpreting results. Plasma NGS-based testing may be the most sensitive approach for ctHPVDNA overall.

Developments and future prospects of personalized medicine in head and neck squamous cell carcinoma diagnoses and treatments

BACKGROUND

Precision healthcare has entered a new era because of the developments in personalized medicine, especially in the diagnosis and treatment of head and neck squamous cell carcinoma (HNSCC). This paper explores the dynamic landscape of personalized medicine as applied to HNSCC, encompassing both current developments and future prospects.

RECENT FINDINGS

The integration of personalized medicine strategies into HNSCC diagnosis is driven by the utilization of genetic data and biomarkers. Epigenetic biomarkers, which reflect modifications to DNA that can influence gene expression, have emerged as valuable indicators for early detection and risk assessment. Treatment approaches within the personalized medicine framework are equally promising. Immunotherapy, gene silencing, and editing techniques, including RNA interference and CRISPR/Cas9, offer innovative means to modulate gene expression and correct genetic aberrations driving HNSCC. The integration of stem cell research with personalized medicine presents opportunities for tailored regenerative approaches. The synergy between personalized medicine and technological advancements is exemplified by artificial intelligence (AI) and machine learning (ML) applications. These tools empower clinicians to analyze vast datasets, predict patient responses, and optimize treatment strategies with unprecedented accuracy.

CONCLUSION

The developments and prospects of personalized medicine in HNSCC diagnosis and treatment offer a transformative approach to managing this complex malignancy. By harnessing genetic insights, biomarkers, immunotherapy, gene editing, stem cell therapies, and advanced technologies like AI and ML, personalized medicine holds the key to enhancing patient outcomes and ushering in a new era of precision oncology.

Advances in Cancer Research: Current and Future Diagnostic and Therapeutic Strategies

Cancers of unknown primary (CUP) exhibit significant cellular heterogeneity and malignancy, which poses significant challenges for diagnosis and treatment. Recent years have seen deeper insights into the imaging, pathology, and genetic characteristics of CUP, driven by interdisciplinary collaboration and the evolution of diagnostic and therapeutic strategies. However, due to their insidious onset, lack of evidence-based medicine, and limited clinical understanding, diagnosing and treating CUP remain a significant challenge. To inspire more creative and fantastic research, herein, we report and highlight recent advances in the diagnosis and therapeutic strategies of CUP. Specifically, we discuss advanced diagnostic technologies, including 12-deoxy-2-[fluorine-18]fluoro-D-glucose integrated with computed tomography (18F-FDG PET/CT) or 68Ga-FAPI (fibroblast activation protein inhibitor) PET/CT, liquid biopsy, molecular diagnostics, self-assembling nanotechnology, and artificial intelligence (AI). In particular, the discussion will extend to the effective treatment techniques currently available, such as targeted therapies, immunotherapies, and bio-nanotechnology-based therapeutics. Finally, a novel perspective on the challenges and directions for future CUP diagnostic and therapeutic strategies is discussed.

Association of circulating tumor HPV16DNA levels and quantitative PET parameters in patients with HPV-positive head and neck squamous cell carcinoma

Circulating tumor DNA (ctDNA), which circulates in the blood after being shed from cancer cells in the body, has recently gained attention as an excellent tumor marker. The purpose of this study was to evaluate whether ct human papillomavirus (HPV) 16 DNA (ctHPV16DNA) levels were associated with quantitative PET parameters in patients with HPV-positive head and neck (HN) squamous cell carcinoma (SCC). Fifty patients with oropharyngeal SCC (OPSCC) and 5 with SCC of unknown primary (SCCUP) before treatment were included. They all underwent blood sampling to test ctHPV16DNA levels and FDG PET-CT examinations. Quantitative PET parameters included SUVmax, metabolic tumor volume (MTV), MTV of whole-body lesions (wbMTV), and 56 texture features. ctHPV16DNA levels were compared to texture features of primary tumors in OPSCC patients (Group A) or the largest primary or metastatic lymph node lesions in OPSCC and SCCUP patients (Group B) and to other PET parameters. Spearman rank correlation test and multiple regression analysis were used to confirm the associations between ctHPV16DNA levels and PET parameters. ctHPV16DNA levels moderately correlated with wbMTV, but not with SUVmax or MTV in Groups A and B. ctHPV16DNA levels exhibited a weak negative correlation with low gray-level zone emphasis in Groups A and B. Multiple regression analysis revealed that wbMTV and high gray-level zone emphasis were the significant factors for ctHPV16DNA levels in Group B. These results were not observed in Group A. This study demonstrated that ctHPV16DNA levels correlated with the whole-body tumor burden and tumor heterogeneity visualized on FDG PET-CT in patients with HPV-positive HNSCC.

It is time to improve the diagnostic workup of oropharyngeal cancer with circulating tumor HPV DNA: Systematic review and meta-analysis

The possibility of detecting circulating tumor HPV DNA (ctHPVDNA) in plasma in patients with oropharyngeal cancer has been demonstrated in several reports. However, these data are from small cohorts and available tests for detection of ctHPVDNA are not fully validated. The aim is to evaluate sensitivity, specificity, and accuracy of ctHPVDNA by ddPCR to define its efficacy in the clinical setting for the diagnosis of HPV + OPSCC. A comprehensive search of three different databases: MEDLINE, Embase, and Cochrane Library databases. A total of 998 patients were evaluated from the 13 studies. OPSSC p16+ were 729, while controls p16- were 269. The meta-analytic study estimated the diagnostic performance of ctHPVDNA as follows: pooled sensitivity and specificity of 0.90 (95% CI: 0.82-0.94) and 0.94 (95% CI: 0.85-0.98), respectively; positive and negative likelihood ratios of 12.6 (95% CI: 4.9-32.1) and 0.05 (95% CI: 0.02-0.13), respectively. ddPCR for ctHPVDNA has good accuracy, sensitivity, and specificity for diagnosis of HPV + OPSCC. ctHPVDNA kinetic represents a great reliable opportunity to improve diagnostic and therapeutic management of cancer patients and could open new perspectives for understanding tumor biology.

Circulating Cell-Free SEPT9 DNA Methylation in Blood Is a Biomarker for Minimal Residual Disease Detection in Head and Neck Squamous Cell Carcinoma Patients

BACKGROUND

Tumorous SEPT9 (septin 9, SEPTIN9) circulating cell-free DNA (ccfDNA) methylation in blood plasma is a powerful biomarker for diagnosis, molecular staging, prognosis, and recurrence monitoring in head and neck squamous cell carcinoma (HNSCC) patients. The present study aimed to evaluate the clinical performance of SEPT9 ccfDNA methylation to detect post-surgical minimal residual disease (MRD) in patients with localized or locally advanced HNSCC treated with curative intent.

METHODS

We applied quasi-digital methylation-specific real-time PCR to quantify SEPT9 ccfDNA methylation levels 2 to 30 days post-surgically in plasma from n = 219 prospectively enrolled HNSCC patients. We tested the associations of SEPT9 ccfDNA methylation with clinicopathological parameters and used Kaplan-Meier and Cox proportional hazards analyses for univariate, pairwise bivariate, and multivariate analyses of disease-free survival.

RESULTS

Of 219 patients, 26.5% (58/219) were post-surgically SEPT9 ccfDNA methylation positive. SEPT9 ccfDNA methylation positivity was significantly associated with tumor site, American Joint Committee on Cancer/Union for International Cancer Control (AJCC/UICC; 8th edition) tumor stage, nodal category and extracapsular extension, lymphatic and vascular invasion, and surgical margin. Bivariate Cox proportional hazards analysis proved post-surgical SEPT9 ccfDNA methylation positivity to be an independent prognostic factor tested together with AJCC/UICC tumor stage (SEPT9: hazard ratio [HR] = 2.43, 95% CI, 1.37-4.30, P = 0.002; AJCC/UICC stage: HR = 1.48, 95% CI, 1.11-1.98, P = 0.008).

CONCLUSIONS

Post-surgical SEPT9 ccfDNA methylation may aid to identify high-risk HNSCC patients who could benefit from an intensified adjuvant treatment and surveillance.

Natural History of Oral HPV Infection among Indigenous South Australians

This study aims to describe the natural history of and identify the risk factors associated with oral human papillomavirus (HPV) infections in an Australian Indigenous cohort. A longitudinal cohort study design, with baseline (2018), 12-month, and 24-month data obtained from Indigenous Australians aged 18+ years in South Australia, was performed. Face-to-face interviews were conducted, and saliva samples for HPV testing were collected at each time point. Basic descriptive analyses were conducted to calculate prevalence, incidence, persistence, clearance, and incidence proportions of any HPV infection. Multivariable logistic regression analyses with adjusted prevalence ratios (PRs) were conducted to identify risk factors associated with oral HPV infection. Among 993 participants with valid saliva samples, 44 HPV types were identified. The prevalence of infection with any oral HPV infection was 51.3%, high-risk HPV was 11%, and types implicated in Heck's disease (HPV 13 or 32) was 37.4%. The incidence, persistence, and clearance of any and high-risk HPV infections were 30.7%, 11.8% and 33.3% vs. 9.3%, 2.8%, and 9%, respectively. Our findings indicate that the prevalence, incidence, and persistence of oral HPV infection in a large sample of Indigenous Australians were high, and clearance was low. Oral sex behaviours and recreational drug use were risk factors associated with incident high-risk HPV infection.

The Clinical Utility of Circulating HPV DNA Biomarker in Oropharyngeal, Cervical, Anal, and Skin HPV-Related Cancers: A Review

Human papillomavirus (HPV) is recognized as being related to a wide variety of known cancers: cervical, oropharyngeal, anal, vaginal, penile, and skin. For some of these cancers, rigorous algorithms for screening, therapeutical interventions, and follow-up procedures have been established. Vaccination using the nonvalent anti-HPV vaccine, which prevents infection regarding the most frequently involved high-risk HPV types (16, 18, 31, 33, 45, 52, and 58) and low-risk HPV types (6 and 11), has also extensively prevented, controlled, and even eradicated HPV infections. Still, even with all of these multidisciplinary interventions, the burden of HPV cancers is still high worldwide. The circulating DNA of HPV-induced cancers is thought to be an adequate biomarker for optimizing the control of these virus-related cancers. We analyzed the literature published in the last 5 years regarding ctDNA and four of the above-mentioned cancers. The most frequently used assay for ctDNA detection was the droplet digital PCR assay, used for the management of therapy in the late stages of cancer. ctDNA could not be used for early detection in any of the studied cancers. The OPSCCs were the most frequent cancers analyzed via ctDNA assays. Larger, properly designed cohort studies might establish the clinical utility of this biomarker.

Circulating Tumor DNA in Human Papillomavirus-Mediated Oropharynx Cancer: Leveraging Early Data to Inform Future Directions

ABSTRACT

Circulating tumor DNA (ctDNA) has become an area of intense study in many solid malignancies including head and neck cancer. This is of particular interest for human papillomavirus-mediated oropharyngeal squamous cell carcinoma as this cohort of patients has excellent survival and is undergoing current clinical trials aimed at treatment de-escalation. Recent studies have demonstrated the prognostic implications of pretreatment ctDNA and the utility of monitoring ctDNA during and posttreatment; however, there is a need for a more critical understanding of ctDNA as it is beginning to be incorporated into clinical trials. This review discusses the current state of ctDNA in oropharynx cancer focusing on ctDNA kinetics and minimal residual disease detection and ends with a discussion of future applications.

Diagnosis and monitoring of virus-associated cancer using cell-free DNA

Viral-associated cancers are a distinct group of malignancies with a unique pathogenesis and epidemiology. Liquid biopsy is a minimally invasive way to identify tumor-associated abnormalities in blood derivatives, such as plasma, to guide the diagnosis, prognosis, and treatment of patients with cancer. Liquid biopsy encompasses a multitude of circulating analytes with the most extensively studied being cell-free DNA (cfDNA). In recent decades, substantial advances have been made toward the study of circulating tumor DNA in nonviral-associated cancers. Many of these observations have been translated to the clinic to improve the outcomes of patients with cancer. The study of cfDNA in viral-associated cancers is rapidly evolving and reveals tremendous potential for clinical applications. This review provides an overview of the pathogenesis of viral-associated malignancies, the current state of cfDNA analysis in oncology, the current state of cfDNA analysis in viral-associated cancers, and perspectives for the future of liquid biopsies in viral-associated cancers.

Circulating HPV DNA in HPV-associated cancers

Human papillomavirus (HPV) infections are the primary cause of almost all cervical cancers, anal cancers, and a variable proportion of other anogenital tumors, as well as head and neck cancers. Circulating HPV DNA (cHPV-DNA) is emerging as a biomarker with extensive potential in the management of HPV-driven malignancies. There has been a rapid advancement in the development of techniques for analyzing cHPV-DNA for the detection, characterization, and monitoring of HPV-associated cancers. As clinical evidence accumulates, it is becoming evident that cHPV-DNA can be used as a diagnostic tool. By conducting clinical trials assessing the clinical utility of cHPV-DNA, the full potential of cHPV-DNA for the screening, diagnosis, and treatment of HPV-related malignancies can be corroborated. In this review, we examine the current landscape of applications for cHPV-DNA liquid biopsies throughout the cancer care continuum, highlighting future opportunities for research and integration into clinical practice.

Clearance Profile of Circulating Tumor Human Papillomavirus DNA During Radiotherapy Predicts Clinical Outcomes in Human Papillomavirus-Related Oropharyngeal Cancer

PURPOSE

This study aimed to examine whether circulating tumor human papillomavirus type 16 (HPV16) DNA (ctHPV16DNA) can help identify patients with locally advanced HPV16-related oropharyngeal squamous cell carcinoma who may benefit from deintensified treatment.

MATERIALS AND METHODS

We serially collected blood samples before, during, and after treatment from 22 patients who received 70 Gy radiotherapy alone and longitudinally quantified ctHPV16DNA using droplet digital polymerase chain reaction. We correlated the clearance profile of ctHPV16DNA with clinical outcomes.

RESULTS

The percentage of patients with detectable ctHPV16DNA decreased after every 10 Gy of radiotherapy. By contrast, the percentage of patients who later developed treatment failure among patients with detectable ctHPV16DNA gradually increased as radiotherapy proceeded, reaching 100% after 60 Gy of radiotherapy. We defined patients with and without detectable ctHPV16DNA after receiving 40 Gy as having slow and rapid clearance profiles, respectively. All 12 patients with a rapid clearance profile remained disease-free after radiotherapy. Of the 10 patients with a slow clearance profile, three had persistent or progressive disease at response evaluation after radiotherapy and one developed distant metastasis during follow-up (ie, four patients experienced treatment failure). The median follow-up for surviving patients was 38.6 months, and the 3-year failure-free survival rates of patients with rapid and slow clearance profiles were 100% and 58%, respectively (P = .02). Neither baseline ctHPV16DNA levels nor metabolic tumor volume was an independent predictor of the pattern of the clearance profile.

CONCLUSION

In patients with HPV16-related oropharyngeal squamous cell carcinoma receiving radiotherapy, a slow ctHPV16DNA clearance profile could prelude unfavorable outcomes. Monitoring ctHPV16DNA is essential for determining the clearance profile, which might help optimize treatment intensity individually.

Circulating Human Papillomavirus DNA in Head and Neck Squamous Cell Carcinoma: Possible Applications and Future Directions

There has been a rising trend in HPV-induced head and neck cancers in the last several decades. This subgroup of squamous cell carcinoma is mostly located in the oropharynx and comprises a subset of patients who are typically younger and without the usual risk factors of smoking and alcohol use. As the prognosis of HPV-induced OPC is more favorable, there is a desire to properly select these patients for de-intensification protocols while identifying individuals who may suffer treatment failure. Here, we describe recent developments in circulating tumor HPV DNA as a marker of HPV-positive oropharyngeal cancer that can potentially be used as a diagnostic tool to stratify patients for de-escalation strategies and to survey for recurrence.

HPV and head and neck cancers: Towards early diagnosis and prevention

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide with an increasing trend of its incidence. Alcohol consumption, smoking, and viral infections, such as the mucosal high-risk (HR) human papillomaviruses (HPVs) are major risk factors for HNSCC development. In particular, HR HPVs are mainly associated with a subset of oropharyngeal squamous cell carcinoma (OPSCC), while other head and neck sites are marginally affected by HPV infection. HPV16 is the most frequently HR HPV type associated with HNSCC. In contrast to the cervix, no screening programs or identifiable pre-malignant lesions have been characterized for HPV-related HNSCC. Therefore, identification of general diagnostic algorithms and HPV biomarkers that could facilitate the early diagnosis, disease evolution and recurrence for HPV-driven HNSCCs are urgently needed. We herein review the role of HPV in HNSCC with a focus on epidemiology, biology, applied diagnostic algorithms and available biomarkers in body fluids as early diagnostic tools in HPV-driven HNSCCs.

The current status of cell‐free human papillomavirus DNA as a biomarker in cervical cancer and other HPV ‐associated tumors: A review

Tumor cells release fragments of their DNA into the circulation, so called cell-free tumor DNA (ctDNA), allowing for analysis of tumor DNA in a simple blood test, that is, liquid biopsy. Cervical cancer is one of the most common malignancies among women worldwide and high-risk human papillomavirus (HR-HPV) is the cause of the majority of cases. HR-HPV integrates into the host genome and is often present in multiple copies per cell and should thus also be released as ctDNA. Such ctHPV DNA is therefore a possible biomarker in cervical cancer. In this review, we first give a background on ctDNA in general and then a comprehensive review of studies on ctHPV DNA in cervical cancer and pre-malignant lesions that may develop in cervical cancer. Furthermore, studies on ctHPV DNA in other HPV related malignancies (eg, head-and-neck and anogenital cancers) are briefly reviewed. We conclude that detection of ctHPV DNA in plasma from patients with cervical cancer is feasible, although optimized protocols and ultra-sensitive techniques are required for sufficient sensitivity. Results from retrospective studies in both cervical cancer and other HPV-related malignancies suggests that ctHPV DNA is a promising prognostic biomarker, for example, for detecting relapses early. This paves the way for larger, preferably prospective studies investigating the clinical value of ctHPV DNA as a biomarker in cervical cancer. However, there are conflicting results whether ctHPV DNA can be found in blood from patients with pre-malignant lesions and further studies are needed to fully elucidate this question.

Evolution of a Paradigm Switch in Diagnosis and Treatment of HPV-Driven Head and Neck Cancer—Striking the Balance Between Toxicity and Cure

More than a decade after the discovery of p16 immunohistochemistry (IHC) as a surrogate for human papilloma virus (HPV)-driven head and neck squamous cell carcinoma (HNSCC), p16-IHC has become a routinely evaluated biomarker to stratify oropharyngeal squamous cell carcinoma (OPSCC) into a molecularly distinct subtype with favorable clinical prognosis. Clinical trials of treatment de-escalation frequently use combinations of biomarkers (p16-IHC, HPV-RNA in situ hybridization, and amplification of HPV-DNA by PCR) to further improve molecular stratification. Implementation of these methods into clinical routine may be limited in the case of RNA by the low RNA quality of formalin-fixed paraffin-embedded tissue blocks (FFPE) or in the case of DNA by cross contamination with HPV-DNA and false PCR amplification errors. Advanced technological developments such as investigation of tumor mutational landscape (NGS), liquid-biopsies (LBx and cell-free cfDNA), and other blood-based HPV immunity surrogates (antibodies in serum) may provide novel venues to further improve diagnostic uncertainties. Moreover, the value of HPV/p16-IHC outside the oropharynx in HNSCC patients needs to be clarified. With regards to therapy, postoperative (adjuvant) or definitive (primary) radiochemotherapy constitutes cornerstones for curative treatment of HNSCC. Side effects of chemotherapy such as bone-marrow suppression could lead to radiotherapy interruption and may compromise the therapy outcome. Therefore, reduction of chemotherapy or its replacement with targeted anticancer agents holds the promise to further optimize the toxicity profile of systemic treatment. Modern radiotherapy gradually adapts the dose. Higher doses are administered to the visible tumor bulk and positive lymph nodes, while a lower dose is prescribed to locoregional volumes empirically suspected to be invaded by tumor cells. Further attempts for radiotherapy de-escalation may improve acute toxicities, for example, the rates for dysphagia and feeding tube requirement, or ameliorate late toxicities like tissue scars (fibrosis) or dry mouth. The main objective of current de-intensification trials is therefore to reduce acute and/or late treatment-associated toxicity while preserving the favorable clinical outcomes. Deep molecular characterization of HPV-driven HNSCC and radiotherapy interactions with the tumor immune microenvironment may be instructive for the development of next-generation de-escalation strategies.