Stromal categorization in early oral tongue cancer

Prognostic Value of Ki-67 in the Invasive Zone of Oral Squamous Cell Carcinoma

BACKGROUND

The molecular profile of cells within the tumor invasive zone, where tumor cells interact with surrounding non-tumor cells, plays a crucial role in defining tumor malignant characteristics, such as the pattern of invasion (POI). Therefore, evaluating the diagnostic value of the proliferation index molecule, Ki-67, in both tumor cells and adjacent non-tumor cells at the invasive zone with different POIs, holds significant clinical importance for oral squamous cell carcinoma (OSCC).

METHODS

This retrospective study included 133 primary OSCC samples, and the spatial pattern of Ki-67 in the tumor invasive zone was analyzed by immunohistochemistry (IHC). The prognostic value of tumor cells and stroma proliferative capacity in different POIs were assessed.

RESULTS

Ki-67 was widely expressed in tumor cells and stroma cells within the invasive zone, and cells in high-invasiveness POIs exhibit higher proliferation. Elevated Ki-67 expression in tumor cells was associated with poor overall survival (OS) and disease-free survival (DFS) in patients, which is independent of POIs. In our study, we identified the expression level of Ki-67 in tumor cells across high-invasiveness POIs as an independent risk factor for OS and DFS in OSCC patiens. Additionally, Ki-67 expression in surrounding non-tumor cells did not significantly correlate with patient survival.

CONCLUSION

The remarkable proliferation characteristic of tumor cells in high-invasiveness POIs of OSCC tumors plays a crucial role in the prognosis of patients.

Desmoplastic reaction in the microenvironment of head and neck and other solid tumors: the therapeutic barrier

Head and neck squamous cell carcinoma (HNSCC) remains a challenge due to limited prognostic biomarkers and therapeutic options. The tumor microenvironment (TME), particularly the desmoplastic reaction (DR) characterized by stromal fibrosis, plays a crucial role in cancer progression and resistance to therapy. This review aims to summarize the biological significance of DR in HNSCC initiation, progression, and treatment resistance. Histologically, DR in HNSCC correlates with invasion patterns and clinical outcomes, affecting disease-free and overall survival. The interaction between cancer-associated fibroblasts (CAFs) and TME influences immune responses, including resistance to immunotherapy. Notably, human papillomavirus-driven HNSCC exhibits distinct DR characteristics that further influence the prognosis. DR promotes epithelial-mesenchymal transition and cancer cell invasion through CAF-mediated extracellular matrix remodeling and signaling pathways such as transforming growth factor-beta. DR also affects bone invasion and chemotherapy resistance by modulating stromal responses. Therapeutic strategies targeting DR and stromal components show promise in overcoming therapeutic resistance including resistance to immune checkpoint inhibitors. Understanding the role of DR in HNSCC biology and its impact on treatment response is critical to developing effective therapeutic interventions.

Tumor Microenvironment-Based Risk Stratification of Oropharyngeal Squamous Cell Carcinoma

BACKGROUND

Evaluation of the prognostic impact of tumor microenvironment (TME) has received attention in recent years. We introduce a TME-based risk stratification for oropharyngeal squamous cell carcinoma (OPSCC).

MATERIAL AND METHODS

A total of 182 patients treated for OPSCC at the Helsinki University Hospital were included. TME-based risk stratification was designed combining tumor-stroma ratio and stromal tumor-infiltrating lymphocytes assessed in hematoxylin and eosin-stained sections.

RESULTS

In multivariable analysis, TME-based risk stratification associated with poor disease-free survival with a hazard ratio (HR) of 2.68 (95% CI 1.11-6.48, p = 0.029). In addition, the proposed risk stratification was associated with poor disease-specific survival (HR 2.687, 95% CI 1.28-5.66, p = 0.009) and poor overall survival (HR 2.21, 95% CI 1.23-3.99, p = 0.008).

CONCLUSION

Our TME-based risk stratification provides a powerful prognostic tool that can be used in daily treatment planning of OPSCC together with tumor-related prognostic markers.

Accumulating evidence from meta-analyses of prognostic studies on oral cancer: towards biomarker-driven patient selection

BACKGROUND

Many histopathologic prognostic markers, identified by routine hematoxylin and eosin (HE) staining, have been proposed for predicting the survival of patients with oral squamous cell carcinoma (OSCC). Subsequently, several meta-analyses have been conducted on these prognostic markers. We sought to analyze the accumulated evidence from these meta-analyses.

METHODS

An electronic database search of PubMed, Scopus, Ovid Medline, Web of Science, and Cochrane Library was conducted to retrieve all meta-analysis articles published on histopathologic prognostic markers of OSCC. The risk of bias of the included studies was analyzed using the Risk of Bias in Systematic Reviews (ROBIS) tool. The synthesis of the results was conducted following the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA).

RESULTS

There were 16 meta-analysis articles published on the histological prognostic markers of OSSC. The accumulated evidence from these meta-analyses highlighted the powerful prognostic value of depth of invasion, tumor thickness, perineural invasion, lymphovascular invasion, worst pattern of invasion, tumor budding, and tumor-stroma ratio. The highest odds ratio (OR) of a relationship between a histopathologic prognostic marker and outcome was for the depth of invasion (OR 10.16, 95% CI 5.05-20.46) and tumor thickness (OR 7.32, 95% CI 5.3-10.1) in predicting lymph node metastasis.

CONCLUSION

The published meta-analyses present robust evidence on the significance of emerging histopathologic markers, namely, worst pattern of invasion, tumor budding, and tumor-stroma ratio. It is time to consider such markers in daily pathology reporting and risk stratification of OSCC.

The prognostic value of tumor-infiltrating lymphocytes in head and neck squamous cell carcinoma: A systematic review and meta-analysis

Head and neck squamous cell carcinoma (HNSCC) is experiencing a rising incidence and mortality worldwide, emphasizing the need for reliable prognostic markers. Tumor-infiltrating lymphocytes (TILs) have emerged as a promising biomarker for predicting HNSCC prognosis, yet no systematic reviews have exclusively focused on hematoxylin and eosin (H&E)-stained formalin-fixed paraffin-embedded (FFPE) samples, which are routinely used in clinical practice. This systematic review and meta-analysis followed the PRISMA guidelines to examine the prognostic value of TILs in HNSCC using H&E-stained FFPE samples. Data were pooled from 43 studies, including 26 studies in a meta-analysis, analyzing 5037 HNSCC samples. We found that a high TIL count associated with a significantly improved overall survival (OS) (HR 0.47, 95 % CI 0.41-0.55, p < 0.0001), disease-free survival (DFS) (HR 0.55, 95 % CI 0.41-0.55, p < 0.0001), and disease-specific survival (DSS) (HR 0.58, 95 % CI 0.46-0.73, p < 0.0001). The heterogeneity was moderate for the pooled analysis (OS: I² = 40 %; DFS: I² = 39 %; DSS: I² = 51 %), but low for the subgroup analysis based on tumor site in oral, oropharyngeal, laryngeal, and nasopharyngeal cancer (OS and DFS: I² = 0-14 %). This review is the first to systematically evaluate TILs in HNSCC using H&E-stained samples, confirming their prognostic value. A high TIL count is associated with improved survival outcomes, suggesting their potential as prognostic biomarkers in clinical settings.

Histological pattern of tumor inflammation and stromal density correlate with patient demographics and immuno-oncologic transcriptional profile in oral squamous cell carcinoma

Introduction

Oral squamous cell carcinoma (OSCC) is the most prevalent oral malignancy, with emerging interest in the characterization of its tumor microenvironment. Herein, we present a comprehensive histological analysis of OSCC stromal density and inflammation and their relationship with patient demographics, clinicopathologic features and immuno-oncologic signatures.

Materials-methods

Eighty-seven completely excised OSCC tissues were prospectively collected and scored for histopathologic inflammatory subtypes [HIS]-inflamed (INF), immune-excluded (IE) and immune-desert (ID), peritumoral stromal inflammation (PTSI), and peritumoral stromal fibrosis (PTSF). Scoring of inflammation was complemented by Semaphorin 4D immunohistochemistry. NanoString differential gene expression (DGE) analysis was conducted for eight OSCC cases representative of the inflammatory and stromal subtypes and the demographic groups.

Results

PTSF correlated with male gender (p = 0.0043), smoking (p = 0.0455), alcohol consumption (p = 0.0044), increased tumor size (p = 0.0054), and advanced stage (p = 0.002). On the contrary, PTSI occurred predominantly in females (p = 0.0105), non-drinkers (p = 0.0329), and small tumors (p = 0.0044). Transcriptionally, decreased cytokine signaling, and oncogenic pathway activation were observed in HIS-IE. Smokers and males displayed decreased global immune-cell levels and myeloid-cell predominance.

Conclusion

Our work describes OSCC stromal and inflammatory phenotypes in correlation with distinct patient groups and DGE, highlighting the translational potential of characterizing the tumor microenvironment for optimal patient stratification.

Stromal categorization of recurrent oral cancer after salvage surgery is associated with survival rates

BACKGROUND

Recurrent oral cancer incurred grave outcome. Tumor microenvironment features, like tumor-infiltrating lymphocytes (TILs) or tumor stromal ratio (TSR) had prognostic significance in various cancers. We aimed to evaluate the impact of stromal categorization which incorporated the stromal TILs and TSR on survival outcomes in recurrent oral cancer.

METHODS

162 patients who received surgery-based treatment between 2010 and 2020 were recruited. Outcomes were 5-year overall survival (OS) and disease-specific survival (DSS). The impact of stromal categorization of recurrent primary tumor or node on 5-year OS and DSS were assessed with the Kaplan-Meier method. Multivariate analysis was performed, incorporating variables at initial treatment and salvage surgery. Patients were further categorized using a survival decision tree.

RESULTS

Mean age was 56.1 (SD, 11.3) years; 153 patients (94.4%) were male; 51 patients (31.5%) had stromal category III. Local recurrence occurred in 94 patients (58%), regional recurrence in 55 (34%), and loco-regional recurrence in 13 (8%). Patients with stromal category III had poorer 5-year OS and DSS. Prior radiotherapy, advanced recurrent stage, positive surgical margin, and stromal category III were independent prognosticators for 5-year OS and DSS. In survival decision tree analysis, patients with prior radiotherapy and stromal category III had the worst outcomes.

CONCLUSION

Stromal categorization is associated with outcomes in recurrent oral cancer. Patients with poor prognosticators, such as stromal categorization III, prior radiation, and advanced stage may require closer follow-up and intensive treatment.

f25, a novel synthetic quinoline derivative, inhibits tongue cancer cell invasion and survival by the PPAR pathway in vitro and vivo

Tongue cancer has a very high incidence in China, and there is a need to develop new anti-tumour drugs against it. We synthesised 31 novel quinoline derivatives to test their anti-tumour activity. A compound referred to as "f25" was identified through screening for its high in vitro toxicity against an oral squamous carcinoma cell line (CAL-27). f25 exhibited significant cytotoxicity against CAL-27 cells (IC50 = 7.70 ± 0.58 μΜ). f25 also inhibited the migration and invasion of CAL-27 cells to a level comparable with that of the chemotherapy agent cisplatin. Moreover, f25 promoted the apoptosis of CAL-27 cells. Transcriptome sequencing and western blotting showed that the mechanism of action of f25 against CAL-27 cells involved the peroxisome proliferator-activated receptor (PPAR) signalling pathway. Specifically, f25 could bind to PPAR-α, PPAR-β, and PPAR-γ and increase their expression. In vivo experiments showed that treatment with f25 led to a reduction in tumour volume in nude mice without significant toxicity. Overall, this study highlights the potential of quinoline compounds (particularly f25) for the design and synthesis of anti-tumour drugs. It also underscores the importance of the PPAR signalling pathway as a target for potential cancer therapies.

Global research trends in tongue cancer from 2000 to 2022: bibliometric and visualized analysis

OBJECTIVES

This study conducts a systematic bibliometric analysis of tongue cancer publications to identify key topics, hotspots, and research distribution.

METHODS

We analyzed tongue cancer publications in the Web of Science core collection database, assessing their quantity and quality. We investigated contributors, including countries, affiliations, journals, authors, and categories, within collaborative networks. Additionally, we synthesized key research findings using various analytical techniques, such as alluvial flow, burstness analysis, cluster analysis, co-occurrence network of associations, and network layer overlay.

RESULTS

From 2000 to 2022, this bibliometric study covers 2205 articles and reviews across 617 journals, involving 72 countries, 2233 institutions, and 11,266 authors. It shows consistent growth, particularly in 2016. Key contributors include China (499 publications), Karolinska Institute (84 publications), Oral Oncology (144 publications), and Tuula Salo (47 publications). Other notable contributors are the USA (16,747 citations), the National Cancer Institute (NCI) (2597 citations), and the Memorial Sloan-Kettering Cancer Center (MSK) (2231 citations). Additionally, there are significant teams led by Tuula Salo and Dalianis. We have identified six primary clusters: #0 apoptosis, #1 depth of invasion, #2 radiotherapy, #3 hpv, #4 tongue cancer, #5 oral cancer. The top ten highly cited documents primarily pertain to epidemiology, prognostic indicators in early-stage oral tongue cancer, and HPV. Additionally, we observed 16 reference clusters, with depth of invasion (#3), young patients (#4), and tumor budding (#6) gaining prominence since 2012, indicating sustained research interests.

CONCLUSIONS

This analysis emphasizes the increasing scholarly interest in tongue cancer research. The bibliometric evaluation highlights pivotal recent research themes such as HPV, depth of invasion, tumor budding, and surgical margins.

CLINICAL RELEVANCE

The bibliometric analysis highlights the key topics and studies which have shaped the understanding and management of tongue cancer.

Cancer-Associated Fibroblast Heterogeneity in Malignancy with Focus on Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) remains an understudied and significant global cancer killer and dismal survival rates have not changed in decades. A better understanding of the molecular basis of OSCC progression and metastasis is needed to develop new approaches for treating this disease. The supportive network surrounding cancer tumor cells known as the tumor microenvironment (TME) has gained increasing interest lately since it performs essential protumorigenic functions. Cancer-associated fibroblasts (CAFs) are one of the main cell types in the TME and are known to play a key role in influencing the biological behavior of tumors. CAFs present a heterogeneity both in phenotype as well as functions, leading to the suggestion of different CAF subtypes in several cancer forms. The task to subtype CAFs in OSCC has, however, just begun, and there is today no united way of subtyping CAFs in this disease. This review aims to define the features of CAFs and to summarize CAF subtype research in malignancy with focus on OSCC including aspects as disease prognosis and therapeutic opportunities.

Tumor Budding Should Be in Oral Cavity Cancer Reporting: A Retrospective Cohort Study Based on Tumor Microenvironment

The utility of histological grading, which is useful in predicting prognosis in many tumors, is controversial for oral squamous cell carcinoma (OSCC). Therefore, new histopathological parameters should be added to histopathology reports of OSCCs. The study aimed to evaluate the parameters of worst invasion pattern (WPOI) and tumor budding in patients with OSCC, to compare them with other histopathological parameters, clinical data and overall survival, and to evaluate these results within the literature. A total of 73 OSCC cases with excisional biopsies were included in this study. WPOI, tumor budding, cell nest size, tumor-stroma ratio, stromal lymphocyte infiltration and stroma type, as well as classical histopathological parameters, were evaluated on hematoxylin-eosin-stained sections. Perineural invasion, lymph node metastases, advanced stage, presence of more than five buds and single cell invasion pattern in univariate survival analyses are characterized by a shortened overall survival time. While there was no significant difference between WPOI results and survival in the survival analysis, WPOI 5 was associated with more frequent lymph node metastasis and advanced stage at the time of diagnosis compared to WPOI 4. We concluded that tumor budding and single-cell invasion should be considered prognostic histopathologic parameters in OSCC.

Multiperspective quantitative tumor-stroma ratio reveals histological areas associated with poor outcomes in oral squamous cell carcinoma

AIMS

Different regions of oral squamous cell carcinoma (OSCC) have particular histopathological characteristics, and the individual histological characteristics of the tumors are poorly understood. Therefore, calculating the proportion of tumor cells in different regions that allow assessment of the prognostic outcomes for OSCC patients would be of great clinical significance.

METHODS AND RESULTS

We established an open-source software-based analytic pipeline that defines the inner tumor and invasive tumor front (ITF) in pancytokeratin-stained whole slide images (WSIs) and quantifies the tumor-stroma ratio (TSR) within the two regions. We applied this method to 114 patients with OSCC and predicted patient prognosis by the TSR. The proportion of tumor area in the inner tumor was generally higher than that in the ITF (p < 0.0001). TSR was an independent prognostic factor for overall survival (OS) (p = 0.016), disease-free survival (DFS) (p = 0.026), and relapse-free survival (RFS) (p = 0.037) in inner tumor, and TSR was an independent prognostic factor for OS (p = 0.00052), DFS (p = 0.035), and metastasis-free survival (MFS) (p = 0.038) in the ITF. Tumor-low status was associated with poorer prognosis. There was a significant correlation between the TSR and perineural invasion (PNI) in the inner tumor (p = 0.009).

CONCLUSIONS

The histopathological characteristics of different regions of OSCC may be used to develop the potential prognostic markers. The TSR of the inner tumor is more targeted in predicting prognosis and accurately assesses the risk of PNI+.

Tumor-Stroma Ratio is a Promising Prognostic Classifier in Oropharyngeal Cancer

Tumor-stroma ratio (TSR) has been analyzed in many tumor types. To date, the clinical significance of TSR has not been investigated in oropharyngeal squamous cell carcinoma (OPSCC). We used a recently introduced recommendation for the assessment of TSR in a large cohort of 182 patients with OPSCC treated at the Helsinki University Hospital. The percentage of tumor-associated stroma was estimated in hematoxylin and eosin (HE)-stained sections and categorized into 2 groups: "stroma-high" (>50%) and "stroma-low" (≤50%). In multivariable analysis, TSR had a significant association with patient survival as stroma-high tumors showed worse disease-free survival (hazard ratio [HR] = 3.22, 95% confidence interval [CI] = 1.43-7.26, P = .005), disease-specific survival (HR = 2.48, 95% CI = 1.29-4.74, P = .006), and overall survival (HR = 2.23, 95% CI = 1.29-3.85, P = .004). The prognostic value of TSR was superior to the Tumor-Node-Metastasis classification. In addition, the significant prognostic value of TSR was demonstrated when analyzing human papillomavirus (HPV)-positive and HPV-negative cases separately (P < .05). In conclusion, TSR is a powerful prognostic indicator in OPSCC. It can be assessed quickly without additional costs using standard HE slides. Owing to its simplicity and reproducibility, TSR can be implemented in routine pathology diagnostics and reporting. Patients with stroma-rich tumors have an increased risk of recurrence and cancer-related mortality and may benefit from appropriate intensive treatment strategies with close follow-up.

Emerging histopathologic markers in early-stage oral tongue cancer: A systematic review and meta-analysis

Although there are many histopathologic prognosticators, grading of early oral tongue squamous cell carcinoma (OTSCC) is still based on morphological cell differentiation which has low prognostic value. Here we summarize the emerging histopathological markers showing powerful prognostic value, but are not included in pathology reports. Using PubMed, Scopus, Ovid Medline, and Web of Science databases, a systematic literature search was preformed to identify early OTSCC studies that investigated the prognostic significance of hematoxylin–eosin‐based histopathologic markers. Our meta‐analysis showed that tumor budding was associated with overall survival (hazard ratio [HR] 2.32; 95% CI 1.40–3.84; p < 0.01) and disease‐specific survival (DSS) (1.89; 95% CI 1.13–3.15; p = 0.02). Worst pattern of invasion was associated with disease‐free survival (DFS) (1.95; 95% CI 1.04–3.64; p = 0.04). Tumor–stroma ratio was also associated with DFS (1.75, 95% CI 1.24–2.48; p < 0.01) and DSS (1.69; 95% CI 1.19–2.42; p < 0.01). Tumor budding, worst pattern of invasion, and tumor–stroma ratio have a promising prognostic value in early OTSCC. The evaluation and reporting of these markers is cost‐effective and can be incorporated in daily practice.

Clinicopathological and Prognostic Significance of Stromal Patterns in Oral Squamous Cell Carcinoma

Background

Stromal patterns (SP), especially desmoplastic reactions, have recently gained attention as indicators of malignant potential in cancer. In this study, we explored the clinicopathological and prognostic significance of the SP in oral squamous cell carcinoma (OSCC).

Materials and Methods

We reviewed 232 cases of surgically resected OSCC that were not treated with neoadjuvant chemoradiotherapy. We categorized the SP of the OSCC into four groups: immune/inflammatory (84 cases), mature (14 cases), intermediate (78 cases), or immature (56 cases).

Results

The SP category was significantly associated with various clinicopathological factors, such as the histological grade, lymphovascular invasion, neural invasion, and a diffuse invasion pattern. For each of the factors, the immune/inflammatory type was associated with favorable categories, while the immature type was associated with unfavorable categories (p ≤ 0.001). The SP category was also shown to be a prognostic predictor: the 5-year relapse-free survival (RFS) rate was 72.0% for the immune/inflammatory type, 66.7% for the intermediate/mature type, and 31.2% for the immature type (p < 0.0001), and the 5-year overall survival (OS) rate was 85.1% for the immune/inflammatory type, 76.4% for the intermediate/mature type, and 50.0% for the immature type (p < 0.0001). In multivariate analyses, the SP category was identified as an independent prognostic factor for RFS and OS.

Conclusion

Our SP categorization method provides valuable prognostic information in OSCC.

Novel pathological predictive factors for extranodal extension in oral squamous cell carcinoma: a retrospective cohort study based on tumor budding, desmoplastic reaction, tumor-infiltrating lymphocytes, and depth of invasion

Background

Extranodal extension (ENE) is a poor prognostic factor for oral squamous cell carcinoma (OSCC). Identifying ENE by clinical and/or radiological examination is difficult, thereby leading to unnecessary neck dissections. Currently, no definitive predictors are available for ENE. Thus, we aimed to determine the histological predictors of ENE by routine histopathological examination using biopsy and surgically resected specimens.

Methods

This retrospective study included 186 surgically resected OSCC and 83 matched biopsy specimens. Clinical features associated with the tumor microenvironment, including desmoplastic reaction (DR), tumor budding (TB), and tumor-infiltrating lymphocytes (TILs), were evaluated using hematoxylin and eosin-stained primary OSCC and neck dissection specimens. These histological features were divided into two groups: DR-immature (DR-I) and DR-mature (DR-M); TB-high (TB-H) and TB-low (TB-L); and TILs-low (TILs-L) and TILs-high (TILs-H). Clinical depth of invasion (cDOI) and pathological DOI (pDOI) were adapted for biopsies and resections, respectively; DOI was evaluated as DOI > 10 mm and DOI ≤ 10 mm. The clinicopathological relationships between these histopathological features and ENE and the independent risk factors for ENE were analyzed. The histological predictors of ENE were evaluated.

Results

The histological status of DR, TILs, and TB present in biopsy and resection specimens showed high accuracy with that of ENE. DR-I, TILs-L, and TB-H were significantly associated with lymph node metastasis, cDOI, and pDOI. Bivariate and multivariate analyses revealed that TB-H and pDOI > 10 mm in resections were independent factors for the presence of ENE (ENE +). The combination of TB-H/pDOI > 10 mm in resection specimens showed high specificity (91%) and accuracy (83%) regarding ENE + . Although there proved to be no independent factors in biopsies, DR-I and TILs-L were significantly associated with ENE + (p < 0.001). The combination of DR-I/TILs-L/cDOI > 10 mm in biopsies exhibited high sensitivity and specificity with ENE + (70% and 77%, respectively, p < 0.001). These histological predictors could detect even minor ENE (< 2 mm).

Conclusions

The tumor microenvironment status in primary OSCC was significantly associated with that of ENE, and TB-H was an independent risk factor for ENE. The histological status of DR-I/TILs-L/cDOI > 10 mm in biopsy specimens and TB-H/pDOI > 10 mm in resection specimens is a useful predictor of ENE.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09393-8.

Shooting at Moving and Hidden Targets-Tumour Cell Plasticity and the Notch Signalling Pathway in Head and Neck Squamous Cell Carcinomas

Head and Neck Squamous Cell Carcinoma (HNSCC) is often aggressive, with poor response to current therapies in approximately 40-50% of the patients. Current therapies are restricted to operation and irradiation, often combined with a small number of standard-of-care chemotherapeutic drugs, preferentially for advanced tumour patients. Only very recently, newer targeted therapies have entered the clinics, including Cetuximab, which targets the EGF receptor (EGFR), and several immune checkpoint inhibitors targeting the immune receptor PD-1 and its ligand PD-L1. HNSCC tumour tissues are characterized by a high degree of intra-tumour heterogeneity (ITH), and non-genetic alterations that may affect both non-transformed cells, such as cancer-associated fibroblasts (CAFs), and transformed carcinoma cells. This very high degree of heterogeneity likely contributes to acquired drug resistance, tumour dormancy, relapse, and distant or lymph node metastasis. ITH, in turn, is likely promoted by pronounced tumour cell plasticity, which manifests in highly dynamic and reversible phenomena such as of partial or hybrid forms of epithelial-to-mesenchymal transition (EMT), and enhanced tumour stemness. Stemness and tumour cell plasticity are strongly promoted by Notch signalling, which remains poorly understood especially in HNSCC. Here, we aim to elucidate how Notch signal may act both as a tumour suppressor and proto-oncogenic, probably during different stages of tumour cell initiation and progression. Notch signalling also interacts with numerous other signalling pathways, that may also have a decisive impact on tumour cell plasticity, acquired radio/chemoresistance, and metastatic progression of HNSCC. We outline the current stage of research related to Notch signalling, and how this pathway may be intricately interconnected with other, druggable targets and signalling mechanisms in HNSCC.

A Case Report of Tongue Lymphoepithelial Carcinoma with a Histological Diagnostic Dilemma

Most head and neck lymphoepithelial carcinomas (LECs) arise in the nasopharynx and harbor Epstein–Barr virus (EBV). LEC is also a rare subtype of the oral squamous cell carcinoma (SCC). Morphologically, LEC is defined as resembling non-keratinizing nasopharyngeal carcinoma, undifferentiated subtype. The histological features and pathogenesis of oral LEC are not established. We describe a case of tongue LEC with histopathological diagnostic difficulties. A 72-year-old Japanese female presented with a whitish change on her left-side tongue. The diagnosis was atypical epithelium; neoplastic change could not be ruled out by a biopsy. Although the lesion was monitored at our hospital per her request, invasive carcinoma was detected 11 months later. Microscopically, conventional SCC was observed with the characteristic features as LEC confined to the deep part of the lesion. We briefly discuss this unusual histological finding and make a novel proposal for distinguishing oral LEC from LECs in other regions based on these histological findings.

Biomarkers for Immunotherapy of Oral Squamous Cell Carcinoma: Current Status and Challenges

Oral squamous cell carcinoma (OSCC) forms a major health problem in many countries. For several decades the management of OSCC consisted of surgery with or without radiotherapy or chemoradiotherapy. Aiming to increase survival rate, recent research has underlined the significance of harnessing the immune response in treatment of many cancers. The promising finding of checkpoint inhibitors as a weapon for targeting metastatic melanoma was a key event in the development of immunotherapy. Furthermore, clinical trials have recently proven inhibitor of PD-1 for treatment of recurrent/metastatic head and neck cancer. However, some challenges (including patient selection) are presented in the era of immunotherapy. In this mini-review we discuss the emergence of immunotherapy for OSCC and the recently introduced biomarkers of this therapeutic strategy. Immune biomarkers and their prognostic perspectives for selecting patients who may benefit from immunotherapy are addressed. In addition, possible use of such biomarkers to assess the response to this new treatment modality of OSCC will also be discussed.