Search Results (1,699)

Background: Accurate differentiation between benign and malignant cervical lymphadenopathy remains clinically important for diagnostic stratification and treatment planning. This study evaluated the diagnostic performance of conventional morphological magnetic resonance imaging (MRI) features and apparent diffusion coefficient (ADC) values in a mixed cohort of cervical lymphadenopathies. Methods: This retrospective lesion-based diagnostic study included 88 cervical lymph nodes from 39 patients who underwent head-and-neck MRI between September 2023 and December 2025. The cohort had malignant entities such as squamous cell carcinoma metastases, thyroid carcinoma, non-Hodgkin lymphoma, adenoid cystic carcinoma, and medullary thyroid carcinoma, as well as benign/reactive, inflammatory, CMV-related, tuberculous, Warthin tumor-associated, and cystic lymphangioma-related lymphadenopathies. MRI examinations were performed for heterogeneous indications, including the initial assessment of palpable cervical lymphadenopathy, oncological staging, post-biopsy follow-up, suspected recurrence, and benign/inflammatory lesion characterization; therefore, not all patients underwent MRI for the same clinical indication. Most examinations were performed during the initial diagnostic work-up, while six cases represented post-biopsy follow-up. Morphological features and ADC values were analyzed using Mann–Whitney U tests, chi-square tests, ROC analysis, DeLong testing, Firth penalized logistic regression, generalized estimating equations (GEE), patient-level bootstrap resampling, and calibration analysis. Statistical analyses were performed using Python (Version 3.12), with exploratory verification in JASP. Statistical significance was set at p < 0.05. Results: The cohort included 39 patients with a mean age of 54 years (range: 18–74 years), with 20 males and 19 females. Of the 88 lymph nodes, 33 were malignant and 55 benign. Malignant nodes demonstrated significantly lower ADC values than benign nodes (0.87 ± 0.23 vs. 1.25 ± 0.22 × 10⁻³ mm²/s; U = 207, p < 0.001). ADC alone showed good diagnostic performance, with an AUC of 0.886 (95% CI: 0.803–0.960). The optimal ADC cutoff was 0.900 × 10⁻³ mm²/s, yielding 75.8% sensitivity and 89.1% specificity. The final GEE model, including the ADC, nodal shape, and margin characteristics while accounting for intra-patient clustering, achieved an apparent AUC of 0.956. Leave-one-patient-out cross-validation yielded an AUC of 0.929, and the bootstrap optimism-corrected AUC was 0.949. DeLong testing confirmed that the combined model significantly outperformed the ADC alone (AUC improvement = 0.070; p = 0.006), and the inter- and intra-observer reproducibility for ADC was excellent. Conclusions: ADC values, nodal shape, and margin characteristics provide complementary diagnostic information for differentiating benign from malignant cervical lymph nodes. A structured multiparametric MRI approach demonstrated high diagnostic performance, although the findings should be interpreted in the context of the retrospective single-center design and histopathological heterogeneity. Full article

Dysregulated microRNA (miR) expression has emerged as a potential prognostic tool in head and neck squamous cell carcinoma (HNSCC), but the clinical value of miR-34a remains unclear. This systematic review, meta-analysis, and trial sequential analysis (TSA) evaluated the association between tumor tissue miR-34a expression and survival outcomes in HNSCC. Following a protocol registered in PROSPERO (n. CRD420251238772), PubMed/MEDLINE, Scopus, ScienceDirect, CENTRAL, Google Scholar, and grey literature sources were searched for studies reporting overall survival (OS) or disease-free survival (DFS) stratified by miR-34a expression in HNSCC or its subsites. Hazard ratios (HRs) were extracted directly or reconstructed from Kaplan–Meier (KM) curves using the Tierney method, supported by a dedicated Python application (KM2HR). Four retrospective studies, corresponding to six study/site-specific cohorts and 318 patients, met the inclusion criteria. For OS (four cohorts), the fixed-effects model yielded a pooled HR of 2.25 (95% CI 1.48–3.41) for low versus high miR-34a expression, indicating worse survival in the low-expression group. However, the random-effects model attenuated the association (HR 1.32, 95% CI 0.32–5.54), with substantial heterogeneity (I² ≈ 77%). For DFS (two studies), the fixed-effects model suggested poorer outcomes with low miR-34a (HR 2.92, 95% CI 1.24–6.88), whereas the random-effects model reversed the direction of effect with extremely wide confidence intervals (HR 0.19, 95% CI ≈ 0.00–129.34; I² = 91%). TSA for OS (accrued information size 225 patients; estimated power ≈66%) crossed the monitoring boundary but did not reach the a priori information size, supporting only a tentative signal. A bioinformatic exploration of the TCGA HNSCC cohort (n = 522) showed a non-significant trend towards worse OS with low miR-34a (HR 1.24, 95% CI 0.93–1.65) and was excluded from pooling. Overall, low tumor miR-34a expression appears to be associated with poorer OS, but the evidence is limited by retrospective design, small sample size, and marked heterogeneity. miR-34a is a promising biomarker for prognostic stratification in HNSCC, yet larger, prospective, site-specific studies with standardized assays, pre-defined cut-offs, and appropriate adjustment for HPV status and clinical covariates are required before clinical implementation can be recommended. Full article

Objective: The aim of this study was to evaluate the expression of PD-L1, PD-1, CD3, CD4, and CD8 in tumor tissues of patients with head and neck squamous cell carcinoma from southern Poland, and to assess their prognostic value in relation to disease-free survival (DFS), taking into account HPV16 status and other clinical, pathological, and demographic factors. Material/Methods: This study included 155 unselected patients with head and neck squamous cell carcinoma (HNSCC) from the southern Poland region, who underwent diagnostic evaluation and surgical treatment. Formalin-fixed, paraffin-embedded (FFPE) tissue blocks were obtained from these centers. The patients were treated at the Maria Skłodowska-Curie National Research Institute of Oncology, Kraków Branch, between 1991 and 2014, with treatment approaches including induction therapy (preoperative), adjuvant therapy (postoperative), or definitive chemoradiotherapy with cisplatin. Protein expression was assessed using immunohistochemistry and quantified (TPS, CPS, H-score). Relationships between expression levels and epidemiological, clinical, and histopathological features were analyzed. Results: The results show that PD-L1 overexpression was associated with worse DFS, whereas overexpression of PD-1, CD3, CD4, and CD8 correlated with improved DFS. These associations were statistically significant in the HPV16-negative subgroup, while no such correlations were found in HPV16-positive patients. In multivariate analysis, independent prognostic factors associated with improved DFS included HPV16 infection, absence of PD-L1 overexpression, overexpression of CD4 and CD8, and combined chemoradiotherapy with cisplatin. Conclusions: These findings confirm the prognostic relevance of PD-L1, PD-1, and T-cell markers in HNSCC, particularly in HPV16-negative patients, and support further research into the use of these biomarkers in personalized treatment strategies. Full article

Background: Understanding lymph node involvement in head and neck cancers is crucial for developing effective treatment strategies and improving patient outcomes. Accurate identification of nodal metastases can enhance prognostic assessment, improve survival rates, and reduce the risk of recurrence. This study aimed to evaluate the association of lymph node metastases with primary tumor characteristics, with a particular focus on tumor stage and primary tumor location in head and neck squamous cell carcinoma (HNSCC). Methods: The study included 170 patients diagnosed with HNSCC at a single medical center between 2022 and 2025. Clinical and pathological assessments of the size and extent of primary tumors were performed according to the American Joint Committee on Cancer TNM classification, version 8. Results: The study cohort consisted of adult patients with a mean age of 61.9 years, of whom 40.6% were female. The tongue was the most common primary tumor site (54.7%), followed by the floor of the mouth (22.4%) and the jaw (8.8%). Clinical staging identified lymph node metastases (cN1 or higher) in 32.4% of patients, whereas pathological evaluation revealed nodal involvement in 38.9%. A statistically significant association was observed between tumor stage and the presence of lymph node metastases (p < 0.001). Additionally, the frequency of nodal metastases varied by anatomical site, with the highest rates observed in tumors of the floor of the mouth and the tongue. Conclusions: These findings suggest that both tumor stage and primary tumor location are associated with an increased risk of lymph node metastases. The results underscore the limitations of clinical staging in detecting nodal disease and highlight the prognostic significance of tumor stage and anatomical site in assessing metastatic risk. Full article

Background and Objectives: Head and neck squamous cell carcinoma (HNSCC) is a biologically heterogeneous malignancy with variable clinical behavior and prognosis. Human papillomavirus (HPV)-associated tumors represent a distinct subgroup; however, data from Eastern European populations remain limited. This study aimed to evaluate the association between HPV DNA status and nodal involvement in a Bulgarian HNSCC cohort and to explore whether HPV genotype distribution is related to nodal involvement and therapeutic strategy. Materials and Methods: A prospective multicenter observational study with a cross-sectional analytical endpoint was conducted. Fifty patients with histologically confirmed HNSCC were included. Clinical and pathological data were collected, and HPV detection and genotyping were performed using molecular-based methods. Associations between HPV-related variables, nodal status (N0 vs. N+), and treatment strategy were evaluated using univariate tests. HPV status reflects DNA detection only and does not confirm transcriptionally active infection. Results: HPV DNA positivity was identified in 15/50 patients (30.0%). A higher proportion of nodal involvement was observed among HPV-positive patients compared with HPV-negative patients (46.7% vs. 17.1%, p = 0.040; crude OR = 4.23); however, this finding may be influenced by anatomical site distribution. In unadjusted analysis, HPV DNA positivity showed a relationship with nodal involvement (crude OR = 4.23; p = 0.040), although this should be interpreted cautiously. Multivariable analysis was not performed due to the limited number of outcome events. Differences in treatment allocation were observed between HPV-positive and HPV-negative patients; however, this finding may be confounded by anatomical site distribution and likely reflects differences in tumor localization rather than HPV-specific effects. Genotype analysis revealed heterogeneity, including multiple HPV types. Conclusions: HPV DNA positivity was observed in relation to nodal involvement in unadjusted analysis; however, this finding may be confounded by anatomical site and should be considered exploratory. Full article

Background: Preoperative assessment of Head and Neck Squamous Cell Carcinoma (HNSCC) aggressiveness is often hindered by the sampling errors of incisional biopsies. While Contrast-Enhanced Computed Tomography (CECT) is the standard for staging, its potential to serve as a non-invasive complementary radiological tool of the entire tumor volume remains underutilized. Objective: To evaluate the predictive performance of preoperative CECT-derived tumor volume, densitometric values, and morphological features as predictors of histopathological grade and lymph node metastasis (pN) in HNSCC. The primary outcome was predicting lymph node metastasis (pN+), and the secondary outcome was predicting histopathological grade. Methods: This retrospective observational study analyzed 42 patients with SCC of the oral cavity, larynx, or maxilla. Quantitative (3D volume, Hounsfield Units [HU], HU Delta) and qualitative (margins, lobulations, necrosis) CT parameters were correlated with definitive histopathology. Diagnostic performance was assessed using Receiver Operating Characteristic (ROC) curve analysis and Spearman’s rank correlation. Results: High-grade tumors (G2/G3) demonstrated significantly larger median volumes (18.1 vs. 2.9 cm³, p = 0.006), lower contrast density (55 vs. 68 HU, p = 0.010), and reduced vascular wash-in (23 vs. 30 HU Delta, p = 0.008) compared to G1 lesions. ROC analysis identified a volume threshold of ≥ 9.43 cm³ for high-grade disease (AUC = 0.865; sensitivity 67.6%, specificity 100%). For regional metastasis (pN+), tumor volume was the only significant predictor (25.4 vs. 6.2 cm³, p = 0.036), with an optimal cut-off of ≥6.76 cm³ (AUC = 0.769; sensitivity 100%). Strong negative correlations were observed between contrast enhancement and internal necrosis (r = −0.812, p < 0.001). Conclusions: Preoperative CECT parameters show promise as non-invasive imaging surrogates of HNSCC aggressiveness. A paradoxical reduction in contrast enhancement characterizes high-grade biology, reflecting disorganized neo-angiogenesis and internal hypoxia. Integrating 3D volumetric analysis and morphological markers shows potential as a complementary exploratory tool that, pending future prospective validation, may support risk stratification and surgical planning alongside traditional histopathological assessment. Full article

Background/Objectives: Distinguishing primary lung squamous cell carcinoma (PLSCC) from metastatic head and neck squamous cell carcinoma (MHNSCC) to the lungs is challenging for pathologists, especially when patients present with a solitary lung nodule. The purpose of this study was to identify CT imaging features that differ between PLSCC from solitary MHNSCC to the lungs, using next-generation sequencing (NGS) and human papillomavirus in situ hybridization analysis as the gold reference standard. Methods: This retrospective, single-institution cross-sectional study included patients with a biopsy-proven PLSCC or solitary MHNSCC from July 2013 to May 2022, who underwent NGS or in situ hybridization, and baseline CT or PET/CT. Each scan was evaluated by at least two radiologists. Nodular, pleural, and ancillary CT features, as well as maximum standardized uptake value (SUVmax) from PET/CTs, were recorded. Associations between imaging features and pathology were examined using either the Wilcoxon rank-sum or Fisher’s exact test. Results: In total, 81 patients were included (median 66 years; 64 male); 36/81 (44%) had PLSCC and 45/81 (56%) had MHNSCC. PLSCC was associated with a larger size (median, 3.3–3.6 cm vs. 1.4–1.6 cm, p < 0.001), and the presence of post obstructive atelectasis (p = 0.002), pleural retraction (p < 0.001), pleural tags (p = 0.02), and pleural surface involvement (p = 0.02). MHNSCC presented as smaller peripheral nodules (p = 0.003) with lower SUVmax (p = 0.01). Conclusions: Several CT imaging features as well as SUVmax from PET/CT were significantly different between PLSCC and solitary MHNSCC and their potential discriminatory ability warrants evaluation in future studies. Full article

Introduction: The role of immune checkpoint inhibitors (ICIs) in locally advanced head and neck squamous cell carcinoma (LA HNSCC) remains uncertain, with randomized trials showing inconsistent results in heterogeneous populations. We conducted a systematic review of randomized trials evaluating ICI-based strategies in LA HNSCC, with outcomes stratified by PD-L1 expression, HPV/p16 status, and cisplatin eligibility to identify patient subgroups most likely to benefit from ICIs. Methods: MEDLINE, Cochrane, and EMBASE databases were systematically searched up to 10 January 2026. Randomized controlled trials (RCTs) evaluating ICIs in patients with LA HNSCC were included. The primary outcome was pooled time-to-event efficacy, including event-free survival (EFS), progression-free survival (PFS), and disease-free survival (DFS) as reported across trials. A generic inverse variance method was used to calculate the estimated pooled hazard ratio (HR) for PFS with 95% confidence interval (CI). Heterogeneity was assessed with Cochran’s Q test. Random effects model was applied. Results: A total of 3605 patients from seven phase II/III RCTs were included. In the overall population, no significant difference in EFS/PFS/DFS was observed between ICI and standard therapy (HR 0.90; 95% CI: 0.77–1.06; p = 0.20). However, in subgroup analyses stratified by PD-L1 expression, patients with PD-L1-positive tumors demonstrated improved PFS with ICIs compared with control (HR 0.78; 95% CI: 0.67–0.91; p < 0.0001). In contrast, PD-L1-negative tumors demonstrated inferior PFS in the ICIs arm (HR 1.31; 95% CI: 1.02–1.68; p = 0.03). No significant differences in PFS were observed based on HPV or p16 status. A subset analysis of cisplatin-eligible LA HNSCC trials evaluating the addition of ICIs to standard therapy showed a similar pattern. ICI use in PD-L1-positive patients demonstrated significantly improved PFS (HR 0.76; 95% CI: 0.63–0.92; p < 0.0001), while ICI use in PD-L1-negative patients demonstrated decreased PFS (HR 1.28; 95% CI: 0.99–1.66; p = 0.06). In cisplatin-ineligible populations, ICI regimens did not improve PFS compared with cetuximab plus RT. Conclusions: This study showed that although in the overall population there was no significant difference in EFS/PFS/DFS, in the PD-L1-positive subgroup, patients experienced significantly improved PFS with ICIs compared with control, while in the PD-L1-negative subgroup, patients demonstrated inferior PFS in the ICIs arm; these results were mirrored in the cisplatin-eligible subgroup. Full article

Oral cancer is a significant public health concern and is among the most common malignant tumors of the head and neck. Its incidence and mortality rates remain persistently high, especially in regions where smoking and betel nut chewing are prevalent. Due to its high mortality rate, early detection is crucial for improving patient outcomes. However, early symptoms of oral cancer often resemble benign oral lesions, leading to delayed diagnosis. In this study, a vision transformer (ViT) model with Optuna (ViTOPT) is employed to perform classification tasks of identifying oral cancer images. The Optuna is used to determine hyperparameters in ViT. Histological images are obtained from a publicly available dataset. Three classification tasks with histological images namely classifying oral squamous cell carcinoma (OSCC) and leukoplakia (LEUK), classifying the presence of dysplasia, and classifying OSCC and leukoplakia with or without dysplasia are performed in this study. Numerical results reveal that the proposed ViTOPT framework is able to provide satisfactory performance in oral cancer recognition. Thus, the proposed ViTOPT model is a feasible and effective alternative in identifying oral cancer. Full article

Background: Immune-related snoRNAs remain largely uncharacterized in cancer. Methods: We comprehensively investigated their functions and clinical relevance through an integrative pan-cancer analysis of The Cancer Genome Atlas (TCGA) datasets. We systematically identified immune-related snoRNAs via partial correlation with immune pathways and GSEA, validated their functions in vitro, and performed molecular subtyping in non-small-cell lung cancer (NSCLC) and head and neck squamous cell carcinoma (HNSC). Results: We established a comprehensive landscape of immune-related snoRNAs associated with core immune pathways, the majority of which were dysregulated across cancers and correlated with tumor immune cell infiltration. Functional screening revealed that numerous immune-related snoRNAs were aberrantly expressed in cancer stem cells; notably, SNORD116-19 potently suppressed breast cancer stemness and metastasis. Using a panel of immune-related snoRNAs, we classified NSCLC into three molecular subtypes with distinct molecular features and immune microenvironments, suggesting divergent immunotherapy response patterns. This classification framework was successfully extrapolated to HNSC. Conclusions: Our findings suggest that immune-related snoRNAs may serve as potential regulators linking tumor progression and immunity and could be explored as candidate biomarkers for molecular subtyping with the potential to inform personalized immunotherapy strategies. Full article

Zinc transport plays a critical role in cellular signaling, but its function in the tumor microenvironment remains poorly understood. We aimed to investigate the role of zinc transporters in cancer-associated fibroblasts in head and neck squamous cell carcinoma. Single-cell RNA sequencing data were analyzed to evaluate zinc transporter expression across tumor cell populations, and bulk RNA sequencing of primary fibroblast cultures was used for validation. Clinical relevance was assessed using transcriptomic and survival data from a large patient cohort. We found that zinc transporter expression, particularly SLC39A13, was enriched in fibroblasts and strongly associated with myofibroblastic activation signatures, including extracellular matrix remodeling and TGFβ signaling. Fibroblasts with high SLC39A13 expression were linked to immunosuppressive tumor environments characterized by reduced cytotoxic T-cell infiltration and increased immunosuppressive cells. Clinically, SLC39A13 expression was associated with poor progression-free survival and remained an independent prognostic factor. These findings suggest that zinc transporter-mediated pathways play a key role in stromal activation and immune regulation, highlighting SLC39A13 as a potential therapeutic target in head and neck squamous cell carcinoma. Full article

Background/Objectives: Preclinical studies of head and neck squamous cell carcinoma (HNSCC) commonly use subcutaneous heterotopic (flank) tumor models for simplicity; however, orthotopic models may better reflect the native tumor environment. Direct comparisons of the tumor immune microenvironments (TIME) and tumor-draining lymph nodes (tdLNs) between these models remain limited. Better understanding of site-specific immune differences could improve model selection and interpretation of translational HNSCC studies. Methods: ROC1 tumors were established in murine heterotopic and orthotopic sites, followed by assessment of tumor growth kinetics, survival, and the tumor microenvironment. Immune composition of tumors, blood, tdLNs, and spleen was evaluated at three tumor progression timepoints using multiparameter spectral flow cytometry. Results: Heterotopic and orthotopic tumor models showed similar growth kinetics and survival. Immune profiling revealed increased infiltration of CD3⁺ T-cells, natural killer (NK) cells, and myeloid populations in both models. Heterotopic tumors were enriched in dendritic cells (DCs), plasmacytoid DCs, and monocytic myeloid-derived suppressor cells (M-MDSCs), whereas orthotopic tumors showed increased macrophages, granulocytic MDSCs, and M-MDSCs. Despite temporal variation, both TIMEs were dominated by macrophages, DCs, and CD3⁺ T-cells. Late-stage heterotopic tumors contained more CD4⁺ T-cells. Reduced T-cell cytotoxicity (PD-1, CD107a) and increased immune checkpoint expression across myeloid cells indicated an immunosuppressive TIME. Systemically, effector cells were preserved despite suppressive cell trafficking, and tdLNs in both models exhibited immunosuppressive PD-L1 expression. Conclusions: Heterotopic and orthotopic ROC1 tumors share key immune features, but site-specific differences in the TIME and tdLNs reveal tissue-dependent regulation. These local effects align with systemic changes, supporting global tumor-associated immunosuppression. Full article

Background: Head and neck squamous cell carcinoma (HNSCC) is among the top 10 most common cancer entities worldwide. For patients with locally advanced, non-metastatic HNSCC, the standard of care treatment often includes concomitant chemoradiotherapy with cisplatin. However, a considerable number of these patients are cisplatin-ineligible. To inform treatment selection for cisplatin-unfit patients undergoing radiotherapy (RT) for HNSCC, a network meta-analysis was performed. Method: In November 2023 a systematic search was conducted and updated in January 2026 searching four electronic databases (Medline, Web of Science, Cochrane Library, and Scopus) to identify randomized controlled trials (RCTs) analyzing overall survival (OS), progression-free survival (PFS), locoregional control (LC) and adverse events (AE) of RT combined with chemo-/immunotherapy with relevance to treatment selection in cisplatin-ineligible patients with HNSCC. Results: From all (15,551) search results, 52 publications concerning 28 RCTs reporting on approximately 7000 patients were included. The therapeutic concepts in the experimental group included all combinations of RT with concurrent systemic therapy, excluding cisplatin-based regimens, and were compared with any control treatment. All studies had sufficient quality for inclusion. None of the systemic agents showed a significant improvement in OS, PFS, or LC compared to cisplatin. Carboplatin + 5-FU and mitomycin C + 5-FU improved LC compared to hyperfractionated accelerated radiotherapy (HART). Compared to cisplatin, durvalumab and cetuximab were associated with less dysphagia, cetuximab with less renal impairment, and panitumumab and cetuximab with less weight loss. Conclusions: Carboplatin + 5-FU and Mitomycin C + 5-FU achieve superior LC compared to HART. Targeted therapy and immunotherapy were associated with less severe AEs. Full article

Fanconi anemia (FA) is a rare inherited disorder associated with impaired DNA repair, characterized by congenital anomalies, bone marrow failure, and a significantly increased risk of developing malignancies, particularly squamous cell carcinoma (SCC) of the head and neck. Treatment options for advanced SCC in FA are limited due to hypersensitivity to DNA-damaging agents. This article presents a unique case of SCC that developed in a 17-year-old patient with FA caused by a homozygous mutation in the FANCA gene. At the age of 10, he received a bone marrow transplant from a compatible related donor. Conditioning therapy included busulfan, thymoglobulin, and fludarabine, while graft-versus-host disease (GvHD) prophylaxis was administered with rituximab, methotrexate, and cyclosporine A. Nevertheless, he developed chronic cutaneous GVHD, which was treated for four years with ruxolitinib and tacrolimus, achieving only partial control. During this period, locally advanced cutaneous SCC (T3N0M0, stage III) manifested on the face. Surgery, radiation therapy, and immunotherapy with pembrolizumab led only to an initial partial response. This first pediatric case of immunotherapy for SCC in FA highlights the challenges of treating this rare patient group. Nevertheless, combining radiation therapy with immunotherapy may represent a possible option for disease control. Full article

The use of proton beam therapy (PBT), as a more precision-targeted radiotherapy technique, is increasing in the treatment of head and neck squamous cell carcinoma (HNSCC). PBT benefits from the precise delivery of the radiation dose to the tumour via the Bragg peak. However, challenges still remain in the treatment of HNSCC with radiotherapy, particularly with tumour radioresistance and recurrence, requiring strategies leading to radiosensitisation. There are added complexities with the use of PBT given the increase in linear energy transfer (LET) at and around the Bragg peak, which can cause an altered cellular response compared to low-LET radiation. Nevertheless, targeting the cellular DNA damage response is considered an important strategy to enhance tumour cell killing caused by radiotherapy. Therefore, using specific inhibitors against the protein kinases ataxia telangiectasia mutated (ATM), ataxia telangiectasia and Rad3-related (ATR) and the DNA-dependent protein kinase catalytic subunit (DNA-Pkcs), we investigated their impact in radiosensitising HPV-negative HNSCC cells to PBT of increasing LET. We demonstrate that inhibitors against ATR (AZD6738), and particularly ATM (AZD1390) and DNA-Pkcs (AZD7648), could significantly decrease clonogenic survival of HNSCC cell lines following PBT at both low and relatively high LET (~2 keV/µm and ~8 keV/µm, respectively). We confirmed that the inhibitors in combination with PBT led to DSB persistence through neutral comet assays and monitoring γH2AX/53BP1 foci. We also show that this strategy can enhance the sensitivity of patient-derived organoids of HNSCC to PBT of both low and high LET, highlighting this as a strategy which should be exploited further. Full article