Advanced diagnostic aids for oral cancer

Multispectral fluorescence imaging of EGFR and PD-L1 for precision detection of oral squamous cell carcinoma: a preclinical and clinical study

BACKGROUND

Early detection and treatment are effective methods for the management of oral squamous cell carcinoma (OSCC), which can be facilitated by the detection of tumor-specific OSCC biomarkers. The epidermal growth factor receptor (EGFR) and programmed death-ligand 1 (PD-L1) are important therapeutic targets for OSCC. Multispectral fluorescence molecular imaging (FMI) can facilitate the detection of tumor multitarget expression with high sensitivity and safety. Hence, we developed Nimotuzumab-ICG and Atezolizumab-Cy5.5 imaging probes, in combination with multispectral FMI, to sensitively and noninvasively identify EGFR and PD-L1 expression for the detection and comprehensive treatment of OSCC.

METHODS

The expression of EGFR and PD-L1 was analyzed using bioinformatics data sources and specimens. Nimotuzumab-ICG and Atezolizumab-Cy5.5 imaging probes were developed and tested on preclinical OSCC cell line and orthotopic OSCC mouse model, fresh OSCC patients' biopsied samples, and further clinical mouthwash trials were conducted in OSCC patients.

RESULTS

EGFR and PD-L1 were specifically expressed in human OSCC cell lines and tumor xenografts. Nimotuzumab-ICG and Atezolizumab-Cy5.5 imaging probes can specifically target to the tumor sites in an in situ human OSCC mouse model with good safety. The detection sensitivity and specificity of Nimotuzumab-ICG in patients were 96.4% and 100%, and 95.2% and 88.9% for Atezolizumab-Cy5.5.

CONCLUSIONS

EGFR and PD-L1 are highly expressed in OSCC, the combination of which is important for a precise prognosis of OSCC. EGFR and PD-L1 expression can be sensitively detected using the newly synthesized multispectral fluorescence imaging probes Nimotuzumab-ICG and Atezolizumab-Cy5.5, which can facilitate the sensitive and specific detection of OSCC and improve treatment outcomes.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR2100045738. Registered 23 April 2021, https://www.chictr.org.cn/bin/project/edit?pid=125220.

Hypomethylation-associated Sox11 upregulation promotes oncogenesis via the PI3K/AKT pathway in OLP-associated OSCC

Oral lichen planus (OLP) is a particularly prevalent oral disorder with the potential to progress to oral squamous cell carcinoma (OSCC). SRY-box transcription factor 11 (Sox11) has been reported to serve as a prognostic marker for various cancers. However, the role and mechanism of Sox11 in OLP-related OSCC are unknown. Our results indicated that Sox11 was highly expressed, and that Sox11 promoter methylation was significantly reduced in OLP-associated OSCC tissues. High Sox11 expression and Sox11 promoter hypomethylation indicate a poor patient prognosis. According to in vivo and in vitro experiments, the knockdown of Sox11 inhibited proliferation, invasion, and migration while driving its apoptotic death in OSSC cells; Sox11 overexpression exerted the opposite effect as Sox11 knockdown. Mechanistically, knockdown of Sox11 inhibited PI3K/AKT and glycolysis pathway, and overexpression of Sox11 enhanced the PI3K/AKT and glycolysis pathways in OSCC cells. In addition, we demonstrated that Sox11 overexpression accelerated the progression of OSCC, at least in part by promoting PI3K/AKT pathway activation. In conclusion, our data indicated that the DNA hypomethylation-associated upregulation of Sox11 could promote oncogenic transformation via the PI3K/AKT pathway in OLP-associated OSCC. Therefore, Sox11 might be a reliable biomarker for predicting the progression of precancerous oral tissues.

Induction of CX3CL1 expression by LPS and its impact on invasion and migration in oral squamous cell carcinoma

Purpose: This study aimed to explore the expression of CX3CL1 induced by lipopolysaccharide (LPS) in oral squamous cell carcinoma (OSCC) and its impact on biological characteristics such as invasion and migration, taking the foundation for new targets for the treatment and prognosis of OSCC. Methods: This study utilized a variety of techniques, including bioinformatics, molecular biology, and cell experiments, to investigate the expression of CX3CL1 and its receptor CX3CR1 in OSCC patients' cancer tissues or OSCC cell lines. Extracting, organizing, and analyzing the TCGA database on the expression of CX3CL1 and its receptor CX3CR1 in cancer tissues and corresponding paracancerous normal tissues of OSCC patients by bioinformatics methods. The expression of CX3CL1 in cancerous and normal tissues of OSCC patients was verified by IHC, and the changes in mRNA and protein expression of CX3CL1 and its receptor CX3CR1 in OSCC cell lines were detected before and after lipopolysaccharide LPS stimulation by RT-PCR, ELISA, and WB. Changes in cell biological behavior by overexpression of CX3CL1 in OSCC cell lines were detected by CCK-8, Transwell, scratch healing assay, and cloning assay. The effects of overexpressing cell lines on the AKT pathway and Epithelial-mesenchymal Transition (EMT)-related protein expression before and after LPS stimulation were detected by Western Blot. Results: (1) CX3CL1 and its receptor CX3CR1 were found to be downregulated in OSCC tissues of patients or OSCC cell lines. (2) After LPS stimulation, CX3CL1 gene expression increased in both OSCC cell lines, while CX3CR1 expression remained unchanged. (3) OSCC cell lines overexpressing CX3CL1 showed changes in cell biological characteristics, including decreased proliferation, invasion, migration, and stemness, which were more pronounced after LPS stimulation. (4) Overexpression of CX3CL1 in OSCC cell lines decreased EMT-related protein expression and AKT phosphorylation. On the contrary were promoted by LPS stimulation. Conclusion: CX3CL1 and CX3CR1 are downregulated in OSCC cancer tissues and cell lines compared to adjacent normal tissues and cells. LPS stimulation increases CX3CL1 expression in OSCC cell lines, suggesting that inflammation may induce CX3CL1 expression and that the CX3CL1 gene may play an important role in OSCC progression. Overexpression of CX3CL1 inhibits OSCC cell proliferation, migration, invasion, and stemness, suggesting that CX3CL1 plays a critical role in suppressing OSCC development. CX3CL1 suppresses OSCC invasion and migration by affecting EMT progression and AKT phosphorylation, and partially reverse the process that LPS causes and affects the development of OSCC.

METTL3 Promotes OSCC Progression by Down-Regulating WEE1 in a m6A-YTHDF2-Dependent Manner

Oral squamous cell carcinoma (OSCC) is a common and highly lethal epithelial cancer. This study aimed to confirm the role of METTL3 in promoting OSCC and investigate its specific underlying mechanisms. Expression of the METTL3, YTH domain-containing family 2 (YTHDF2), and WEE1 were examined in normal oral epithelial cells and OSCC cells. Cell functions were examined after overexpressing WEE1 in OSCC cells. MeRIP-qPCR analysis was used to detect WEE1 m6A levels in HOK, SCC25, and CAL27 cells. WEE1 and its m6A levels were evaluated in OSCC cells by knocking down METTL3/YTHDF2, assessing the interaction between METTL3/YTHDF2 and WEE1. The impact of METTL3 and YTHDF2 downregulation on WEE1 mRNA stability was also investigated. The tumor weight and volume in a nude mouse model of OSCC after overexpression of WEE1 and YTHDF2 were measured. Expression of Ki-67 and WEE1 in OSCC tissue was detected using immunohistochemistry. Compared to normal oral epithelial cells, METTL3 and YTHDF2 were upregulated in OSCC cells, while WEE1 was downregulated, and there was a negative correlation between WEE1 and METTL3/YTHDF2 expression. WEE1 overexpression inhibited proliferation, invasion, and migration while promoting apoptosis in OSCC cells. METTL3 and YTHDF2 bound to WEE1 mRNA. METTL3/YTHDF2 knockdown increased WEE1 levels and WEE1 mRNA stability. METTL3 inhibition reduced WEE1 m6A levels. Inhibition of METTL3 weakened the interaction between YTHDF2 and WEE1 mRNA. In vivo, overexpression of WEE1 suppressed OSCC development, which was reversed by overexpression of YTHDF2. METTL3 facilitates the progression of OSCC through m6A-YTHDF2-dependent downregulation of WEE1.

Prognostic significance of RKIP, TGM2, and CMTM4 expression in oral squamous cell carcinoma

BACKGROUND

The expression of RKIP, TGM2, and CMTM4 in oral squamous cell carcinoma (OSCC) and normal oral tissues was detected and their correlations were analyzed. The relationships between RKIP, TGM2, and CMTM4 and the clinicopathological parameters and prognosis of patients were analyzed.

METHODS

Seventy cancerous and adjacent normal tissue samples were selected, recorded in the pathology department, and embedded in paraffin. Protein expression was detected by immunohistochemistry. Statistical software (SPSS 25.0, IBM Corporation) was used for the statistical analysis. The chi-squared (χ2) test was used to analyze the expression of RKIP, TGM2, and CMTM4 proteins and their clinicopathological features. Differences in RKIP, TGM2, and CMTM4 protein levels between OSCC and normal tissues were compared using a χ2 test. Survival analysis was performed using the Kaplan-Meier method, and differences between survival curves were determined using the log-rank test. The effects of RKIP, TGM2, and CMTM4 expression on patient prognosis were analyzed using a multivariate Cox proportional hazards regression model. P < .05 was considered statistically significant.

RESULTS

The expression level of RKIP correlated with age and clinical stage (P < .05). TGM2 was associated with clinical stage and lymph node metastasis (P < .05). The expression of CMTM4 increased with a decrease in cancer differentiation. Kaplan-Meier survival analysis suggested that the positive expression of TGM2 and CMTM4 may predict poor prognosis in patients with OSCC. The multivariate Cox proportional hazards regression model suggested that TGM2 could be an independent prognostic factor for patients with OSCC.

CONCLUSION

Combined expression of TGM2 and CMTM4 can be used as an indicator to evaluate the risk of metastasis and prognosis of OSCC.

Mechanisms and Potential Clinical Implications of Oral Microbiome in Oral Squamous Cell Carcinoma

Microorganisms in the oral cavity are abundant in the human body. At present, more than 700 species of oral microorganisms have been identified. Recently, a lot of literature has indicated that the oral microbiota plays an important role in the occurrence, development, and prognosis of oral squamous cell carcinoma (OSCC) through various mechanisms. And researchers are now trying to utilize oral microbiota in cancer diagnosis and treatment. However, few articles systematically summarize the effects of oral microbes in the diagnosis, treatment, and disease outcomes of oral cancer. Herein, we made a summary of the microbial changes at cancerous sites and placed more emphasis on the mechanisms by which the oral microbiome promotes cancerization. Moreover, we aimed to find out the clinical value of the oral microbiome in OSCC.

Glucose upregulates amphiregulin in oral dysplastic keratinocytes: A potential role in diabetes-associated oral carcinogenesis

BACKGROUND

Compelling evidence implicates diabetes-associated hyperglycemia as a promoter of tumor progression in oral potentially malignant disorders (OPMD). Yet, information on hyperglycemia-induced cell signaling networks in oral oncology remains limited. Our group recently reported that glucose-rich conditions significantly enhance oral dysplastic keratinocyte viability and migration through epidermal growth factor receptor (EGFR) activation, a pathway strongly linked to oral carcinogenesis. Here, we investigated the basal metabolic phenotype in these cells and whether specific glucose-responsive EGFR ligands mediate these responses.

METHODS

Cell energy phenotype and lactate concentration were evaluated via commercially available assays. EGFR ligands in response to normal (5 mM) or high (20 mM) glucose were analyzed by quantitative real-time PCR, ELISA, and western blotting. Cell viability and migration assays were performed in the presence of pharmacological inhibitors or RNA interference.

RESULTS

When compared to normal keratinocytes, basal glycolysis in oral dysplastic keratinocytes was significantly elevated. In highly glycolytic cells, high glucose-activated EGFR increasing viability and migration. Notably, we identified amphiregulin (AREG) as the predominant glucose-induced EGFR ligand. Indeed, enhanced cell migration in response to high glucose was blunted by EGFR inhibitor cetuximab and AREG siRNA. Conversely, AREG treatment under normal glucose conditions significantly increased cell viability, migration, lactate levels, and expression of glycolytic marker pyruvate kinase M2.

CONCLUSION

These novel findings point to AREG as a potential high glucose-induced EGFR activating ligand in highly glycolytic oral dysplastic keratinocytes. Future studies are warranted to gain more insight into the role of AREG in hyperglycemia-associated OPMD tumor progression.

The emerging role of oral microbiota in oral cancer initiation, progression and stemness

Oral squamous cell carcinoma (OSCC) is the most prevalent malignancy among the Head and Neck cancer. OSCCs are highly inflammatory, immune-suppressive, and aggressive tumors. Recent sequencing based studies demonstrated the involvement of different oral microbiota in oral cavity diseases leading OSCC carcinogenesis, initiation and progression. Researches showed that oral microbiota can activate different inflammatory pathways and cancer stem cells (CSCs) associated stemness pathways for tumor progression. We speculate that CSCs and their niche cells may interact with the microbiotas to promote tumor progression and stemness. Certain oral microbiotas are reported to be involved in dysbiosis, pre-cancerous lesions, and OSCC development. Identification of these specific microbiota including Human papillomavirus (HPV), Porphyromonas gingivalis (PG), and Fusobacterium nucleatum (FN) provides us with a new opportunity to study the bacteria/stem cell, as well as bacteria/OSCC cells interaction that promote OSCC initiation, progression and stemness. Importantly, these evidences enabled us to develop in-vitro and in-vivo models to study microbiota interaction with stem cell niche defense as well as CSC niche defense. Thus in this review, the role of oral microbiota in OSCC has been explored with a special focus on how oral microbiota induces OSCC initiation and stemness by modulating the oral mucosal stem cell and CSC niche defense.

PTP4A1 promotes oral squamous cell carcinoma (OSCC) metastasis through altered mitochondrial metabolic reprogramming

PTP4A1 (Protein tyrosine phosphatase 4A1) is a protein tyrosine phosphatase that regulates a range of pro-oncogenic signaling pathways. Here, we report a novel role for PTP4A1 in oral squamous cell carcinoma (OSCC) growth and development. We show that PTP4A1 is frequently overexpressed in OSCC cells and tissues compared to adjacent non-tumor tissue. In OSCC, the overexpression of PTP4A1 increased cell growth and invasion in vitro, and enhanced tumor progression in vivo. At the molecular level, PTP4A1 was found to regulate mitochondrial metabolic reprogramming to enhance the invasive capacity of OSCC cells. Mechanistically, these effects were mediated through binding to pyruvate kinase isoenzyme M2 (PKM2) to promote its expression and aconitase 2 (ACO2) to enhance its degradation. Together, these data reveal PTP4A1 as a viable target for OSCC therapeutics.

Role of Advanced Diagnostic Aids in the Detection of Potentially Malignant Disorders and Oral Cancer at an Early Stage

One of the most prevalent malignancies diagnosed today is cancer of the mouth or oral cancer. Compared to systemic malignancies like lung cancer, colon cancer, etc., oral cancer tends to get less attention from the general public. However, these lesions may be lethal if not treated, even if diagnosed early. Early diagnosis improves the prognosis for successful therapy. Delayed diagnosis is hypothesized to be a pivotal contributor to the dismal oral cancer survival rate over five years. The current standard of care for diagnosis and detection is based on clinical evaluation, the histological study of biopsy material, and genetic methods. There have been several advancements in the diagnostic technologies available to detect oral cancer at the initial phase. This study aims to dissect the cutting-edge methods for detecting oral cancer in its earliest stages.

The Use of Salivary Levels of Matrix Metalloproteinases as an Adjuvant Method in the Early Diagnosis of Oral Squamous Cell Carcinoma: A Narrative Literature Review

Oral squamous cell carcinoma (OSCC) is an aggressive malignancy with increased mortality, in which the early diagnosis is the most important step in increasing patients' survival rate. Extensive research has evaluated the role of saliva as a source of diagnostic biomarkers, among which matrix metalloproteinases (MMPs) have shown a valuable potential for detecting even early stages of OSCC. The aim of this review was to present recent clinical data regarding the significance of salivary MMPs in the detection of early malignant transformation of the oral mucosa. A narrative review was conducted on articles published in PubMed, Cochrane Library, Web of Science, EBSCO and SciELO databases, using specific terms. Our search revealed that MMP-1, MMP-2, MMP-3, MMP-8, MMP-9, MMP-10, MMP-12 and MMP-13 had significantly higher levels in saliva from patients with OSCC compared to controls. However, the strength of evidence is limited, as most information regarding their use as adjuvant diagnostic tools for OSCC comes from studies with a low number of participants, variable methodologies for saliva sampling and diagnostic assays, and insufficient adjustment for all covariates. MMP-1, MMP-3 and MMP-9 were considered the most promising candidates for salivary diagnosis of OSCC, but larger studies are needed in order to validate their clinical application.

Automated Nuclear Segmentation in Head and Neck Squamous Cell Carcinoma Pathology Reveals Relationships between Cytometric Features and ESTIMATE Stromal and Immune Scores

The tumor microenvironment (TME) plays an important role in the progression of head and neck squamous cell carcinoma (HNSCC). Currently, pathologic assessment of TME is nonstandardized and subject to observer bias. Genome-wide transcriptomic approaches to understanding the TME, while less subject to bias, are expensive and not currently a part of the standard of care for HNSCC. To identify pathology-based biomarkers that correlate with genomic and transcriptomic signatures of TME in HNSCC, cytometric feature maps were generated in a publicly available data set from a cohort of patients with HNSCC, including whole-slide tissue images and genomic and transcriptomic phenotyping (N = 49). Cytometric feature maps were generated based on whole-slide nuclear detection, using a deep-learning algorithm trained for StarDist nuclear segmentation. Cytometric features in each patient were compared to transcriptomic measurements, including Estimation of Stromal and Immune Cells in Malignant Tumor Tissues Using Expression Data (ESTIMATE) scores and stemness scores. With correction for multiple comparisons, one feature (nuclear circularity) demonstrated a significant linear correlation with ESTIMATE stromal score. Two features (nuclear maximum and minimum diameter) correlated significantly with ESTIMATE immune score. Three features (nuclear solidity, nuclear minimum diameter, and nuclear circularity) correlated significantly with transcriptomic stemness score. This study provides preliminary evidence that observer-independent, automated tissue-slide analysis can provide insights into the HNSCC TME which correlate with genomic and transcriptomic assessments.

Liquid Biopsy and Circulating Biomarkers for the Diagnosis of Precancerous and Cancerous Oral Lesions

Oral cancer is one of the most common malignancies worldwide, accounting for 2% of all cases annually and 1.8% of all cancer deaths. To date, tissue biopsy and histopathological analyses are the gold standard methods for the diagnosis of oral cancers. However, oral cancer is generally diagnosed at advanced stages with a consequent poor 5-year survival (~50%) due to limited screening programs and inefficient physical examination strategies. To address these limitations, liquid biopsy is recently emerging as a novel minimally invasive tool for the early identification of tumors as well as for the evaluation of tumor heterogeneity and prognosis of patients. Several studies have demonstrated that liquid biopsy in oral cancer could be useful for the detection of circulating biomarkers including circulating tumor DNA (ctDNA), microRNAs (miRNAs), proteins, and exosomes, thus improving diagnostic strategies and paving the way to personalized medicine. However, the application of liquid biopsy in oral cancer is still limited and further studies are needed to better clarify its clinical impact. The present manuscript aims to provide an updated overview of the potential use of liquid biopsy as an additional tool for the management of oral lesions by describing the available methodologies and the most promising biomarkers.

Prognostic significance of a 4-lncRNA glycolysis-related signature in oral squamous cell carcinoma

BACKGROUND/PURPOSE

Oral squamous cell carcinoma (OSCC) is a highly malignant tumor, and the overall survival (OS) time of patients with OSCC varies considerably. This study aimed to identify reliable biomarkers for OSCC and construct a new prognostic signature, which may guide personalized precision treatment.

MATERIALS AND METHODS

Transcriptome array data of 317 patients with OSCC from The Cancer Genome Atlas Project (TCGA) cohort were retrospectively analyzed. Single-sample gene set enrichment analysis (ssGSEA) and univariate Cox regression were performed to identify the prognostic significance of the hallmarks of each tumor in OSCC. Subsequently, lncRNAs related to glycolysis were identified through co-expression analysis. A glycolysis-related prognostic signature was constructed by combining univariate Cox regression, least absolute shrinkage and selection operator (Lasso) regression, and multivariate Cox regression analyses. Additionally, the infiltration of immune cells in OSCC was evaluated based on data from ssGSEA and TIMER databases.

RESULTS

Glycolysis was identified as the main risk factor for OS in a variety of cancer hallmarks. The 4-lncRNA glycolysis prognostic signature could distinguish high and low-risk patients. This risk signature was found to be an independent prognostic risk factor for OSCC, showing good predictive power compared with other clinicopathological indicators. Immune correlation analysis showed that patients in the low-risk group exhibited higher levels of immune cell infiltration.

CONCLUSION

The novel 4-lncRNA prognostic signature can predict the clinical outcome of patients with OSCC well, and it is expected to become a promising prognostic biomarker as well as a potential therapeutic target in the future.

Identification of Metabolism-Associated Biomarkers for Early and Precise Diagnosis of Oral Squamous Cell Carcinoma

The 5-year survival rate for oral squamous cell carcinoma (OSCC), one of the most common head and neck cancers, has not improved in the last 20 years. Poor prognosis of OSCC is the result of failure in early and precise diagnosis. Metabolic reprogramming, including the alteration of the uptake and utilisation of glucose, amino acids and lipids, is an important feature of OSCC and can be used to identify its biomarkers for early and precise diagnosis. In this review, we summarise how recent findings of rewired metabolic networks in OSCC have facilitated early and precise diagnosis of OSCC.

Clinical assessment for the detection of oral cavity cancer and potentially malignant disorders in apparently healthy adults

BACKGROUND

The early detection of oral cavity squamous cell carcinoma (OSCC) and oral potentially malignant disorders (OPMD), followed by appropriate treatment, may improve survival and reduce the risk for malignant transformation respectively. This is an update of a Cochrane Review first published in 2013.

OBJECTIVES

To estimate the diagnostic test accuracy of conventional oral examination, vital rinsing, light-based detection, mouth self-examination, remote screening, and biomarkers, used singly or in combination, for the early detection of OPMD or OSCC in apparently healthy adults.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 20 October 2020), MEDLINE Ovid (1946 to 20 October 2020), and Embase Ovid (1980 to 20 October 2020). The US National Institutes of Health Trials Registry (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases. We conducted citation searches, and screened reference lists of included studies for additional references.

SELECTION CRITERIA

We selected studies that reported the test accuracy of any of the aforementioned tests in detecting OPMD or OSCC during a screening procedure. Diagnosis of OPMD or OSCC was provided by specialist clinicians or pathologists, or alternatively through follow-up.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened titles and abstracts for relevance. Eligibility, data extraction, and quality assessment were carried out by at least two authors independently and in duplicate. Studies were assessed for methodological quality using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2). We reported the sensitivity and specificity of the included studies. We provided judgement of the certainty of the evidence using a GRADE assessment.

MAIN RESULTS

We included 18 studies, recruiting 72,202 participants, published between 1986 and 2019. These studies evaluated the diagnostic test accuracy of conventional oral examination (10 studies, none new to this update), mouth self-examination (four studies, two new to this update), and remote screening (three studies, all new to this update). One randomised controlled trial of test accuracy directly evaluated conventional oral examination plus vital rinsing versus conventional oral examination alone. There were no eligible studies evaluating light-based detection or blood or salivary sample analysis (which tests for the presence of biomarkers for OPMD and OSCC). Only one study of conventional oral examination was judged as at overall low risk of bias and overall low concern regarding applicability. Given the clinical heterogeneity of the included studies in terms of the participants recruited, setting, prevalence of the target condition, the application of the index test and reference standard, and the flow and timing of the process, the data could not be pooled within the broader categories of index test. For conventional oral examination (10 studies, 25,568 participants), prevalence in the test accuracy sample ranged from 1% to 51%. For the seven studies with prevalence of 10% or lower, a prevalence more comparable to the general population, the sensitivity estimates were variable, and ranged from 0.50 (95% confidence interval (CI) 0.07 to 0.93) to 0.99 (95% CI 0.97 to 1.00); the specificity estimates were more consistent and ranged from 0.94 (95% CI 0.88 to 0.97) to 0.99 (95% CI 0.98 to 1.00). We judged the overall certainty of the evidence to be low, and downgraded for inconsistency and indirectness. Evidence for mouth self-examination and remote screening was more limited. We judged the overall certainty of the evidence for these index tests to be very low, and downgraded for imprecision, inconsistency, and indirectness. We judged the evidence for vital rinsing (toluidine blue) as an adjunct to conventional oral examination compared to conventional oral examination to be moderate, and downgraded for indirectness as the trial was undertaken in a high-risk population.

AUTHORS' CONCLUSIONS

There is a lack of high-certainty evidence to support the use of screening programmes for oral cavity cancer and OPMD in the general population. Frontline screeners such as general dentists, dental hygienists, other allied professionals, and community healthcare workers should remain vigilant for signs of OPMD and OSCC.

Advancements in diagnostic techniques for oral cancer detection

Oral malignancy is among the highest prevalent malignancies all over the world. In comparison to systemic malignancies such as lung cancer and colon cancer, they are frequently overlooked by the general public. Nevertheless, they can be exceedingly lethal if left ignored, regardless at the early stage of the condition. Dentists are the finest qualified healthcare specialists in this sector and are responsible for detecting benign and potentially malignant oral conditions such as oral cancers. Oral carcinoma's high prevalence and delayed appearance are serious international medical concerns. Early detection and management of oral carcinoma are the key goals of the World Health Organization (WHO). The identification of key clinical manifestations during the preliminary oral examination can enhance the patient's likelihood of living. Unfortunately, the conventional technology's practical value is limited by a number of drawbacks. Current advancements in optical scanning techniques, such as tissue-fluorescence imaging and optical coherence tomography, have proven to be quite effective. In particular, nanoparticle-based immunosensors, genomics, and salivary biomarkers, epigenetics and microarray have all received a lot of attention. Raising awareness about frequent dental examinations and using noninvasive, effective, and cost-effective screening tools would improve initial stage detection of oral carcinoma and improve patients' longevity.

Overview of oral cavity squamous cell carcinoma: Risk factors, mechanisms, and diagnostics

Oral cavity squamous cell carcinoma (OCSCC) is the most common malignancy of the oral cavity. The substantial risk factors for OCSCC are the consumption of tobacco products, alcohol, betel quid, areca nut, and genetic alteration. However, technological advancements have occurred in treatment, but the survival decreases with late diagnosis; therefore, new methods are continuously being investigated for treatment. In addition, the rate of secondary tumor formation is 3-7% yearly, which is incomparable to other malignancies and can lead to the disease reoccurrence. Oral cavity cancer (OCC) arises from genetic alterations, and a complete understanding of the molecular mechanism involved in OCC is essential to develop targeted treatments. This review aims to update the researcher on oral cavity cancer, risk factors, genetic alterations, molecular mechanism, classification, diagnostic approaches, and treatment.

Diagnostic tests for oral cancer and potentially malignant disorders in patients presenting with clinically evident lesions

BACKGROUND

Squamous cell carcinoma is the most common form of malignancy of the oral cavity, and is often proceeded by oral potentially malignant disorders (OPMD). Early detection of oral cavity squamous cell carcinoma (oral cancer) can improve survival rates. The current diagnostic standard of surgical biopsy with histology is painful for patients and involves a delay in order to process the tissue and render a histological diagnosis; other diagnostic tests are available that are less invasive and some are able to provide immediate results. This is an update of a Cochrane Review first published in 2015.

OBJECTIVES

Primary objective: to estimate the diagnostic accuracy of index tests for the detection of oral cancer and OPMD, in people presenting with clinically evident suspicious and innocuous lesions.

SECONDARY OBJECTIVE

to estimate the relative accuracy of the different index tests.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following databases: MEDLINE Ovid (1946 to 20 October 2020), and Embase Ovid (1980 to 20 October 2020). The US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were also searched for ongoing trials to 20 October 2020. No restrictions were placed on the language or date of publication when searching the electronic databases. We conducted citation searches, and screened reference lists of included studies for additional references.

SELECTION CRITERIA

We selected studies that reported the diagnostic test accuracy of the following index tests when used as an adjunct to conventional oral examination in detecting OPMD or oral cavity squamous cell carcinoma: vital staining (a dye to stain oral mucosa tissues), oral cytology, light-based detection and oral spectroscopy, blood or saliva analysis (which test for the presence of biomarkers in blood or saliva).

DATA COLLECTION AND ANALYSIS

Two review authors independently screened titles and abstracts for relevance. Eligibility, data extraction and quality assessment were carried out by at least two authors, independently and in duplicate. Studies were assessed for methodological quality using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2). Meta-analysis was used to combine the results of studies for each index test using the bivariate approach to estimate the expected values of sensitivity and specificity.

MAIN RESULTS

This update included 63 studies (79 datasets) published between 1980 and 2020 evaluating 7942 lesions for the quantitative meta-analysis. These studies evaluated the diagnostic accuracy of conventional oral examination with: vital staining (22 datasets), oral cytology (24 datasets), light-based detection or oral spectroscopy (24 datasets). Nine datasets assessed two combined index tests. There were no eligible diagnostic accuracy studies evaluating blood or salivary sample analysis. Two studies were classed as being at low risk of bias across all domains, and 33 studies were at low concern for applicability across the three domains, where patient selection, the index test, and the reference standard used were generalisable across the population attending secondary care. The summary estimates obtained from the meta-analysis were: - vital staining: sensitivity 0.86 (95% confidence interval (CI) 0.79 to 0.90) specificity 0.68 (95% CI 0.58 to 0.77), 20 studies, sensitivity low-certainty evidence, specificity very low-certainty evidence; - oral cytology: sensitivity 0.90 (95% CI 0.82 to 0.94) specificity 0.94 (95% CI 0.88 to 0.97), 20 studies, sensitivity moderate-certainty evidence, specificity moderate-certainty evidence; - light-based: sensitivity 0.87 (95% CI 0.78 to 0.93) specificity 0.50 (95% CI 0.32 to 0.68), 23 studies, sensitivity low-certainty evidence, specificity very low-certainty evidence; and - combined tests: sensitivity 0.78 (95% CI 0.45 to 0.94) specificity 0.71 (95% CI 0.53 to 0.84), 9 studies, sensitivity very low-certainty evidence, specificity very low-certainty evidence.

AUTHORS' CONCLUSIONS

At present none of the adjunctive tests can be recommended as a replacement for the currently used standard of a surgical biopsy and histological assessment. Given the relatively high values of the summary estimates of sensitivity and specificity for oral cytology, this would appear to offer the most potential. Combined adjunctive tests involving cytology warrant further investigation. Potentially eligible studies of blood and salivary biomarkers were excluded from the review as they were of a case-control design and therefore ineligible. In the absence of substantial improvement in the tests evaluated in this updated review, further research into biomarkers may be warranted.

Full-Thickness Tumor Resection of Oral Cancer Involving the Facial Skin-Microsurgical Reconstruction of Extensive Defects after Radical Treatment of Advanced Squamous Cell Carcinoma

Simple Summary

Advanced malignant tumors of the oral cavity are challenging because they impose serious oncological and functional requirements on the treatment specialist. Depending on the localization and the extent of the primary tumor, a full-thickness resection affecting the facial skin may be necessary to achieve a complete tumor resection. The resulting defects need adequate reconstruction in order to restore the aesthetics and functionality of the orofacial system. In this retrospective analysis, the authors aimed to evaluate treatment techniques for these tumors and analyze the clinical outcome of the related procedures. Full-thickness tumor resection with free flap reconstruction due to advanced cancer was performed in 33 patients.

Abstract

Advanced tumors of the head and neck are challenging for the treatment specialist due to the need to synergize oncological and functional requirements. Free flap reconstruction has been established as the standard of care for defects following tumor resection. However, depending on the affected anatomic subsite, advanced tumors may impose specific difficulties regarding reconstruction, especially when full-thickness resection is required. This study aimed to evaluate reconstructive strategies and oncological outcomes in patients with full-thickness resection of the oral cavity. A total of 33 patients with extensive defects due to squamous cell carcinoma of the oral cavity were identified. Indications, reconstructive procedures, and clinical outcome were evaluated. Thirty-two patients (97%) presented locally advanced tumors (T3/T4). Complete tumor resection was achieved in 26 patients (78.8%). The anterolateral thigh flap was the most frequently used flap (47.1%), and the primary flap success rate was 84.8%. The cohort demonstrated a good local control rate and moderate overall and progression-free survival rates. Most patients regained full competence regarding oral alimentation and speech. Full-thickness tumor resections of the head and neck area may be necessary due to advanced tumors in critical anatomic areas. In many cases, radical surgical treatment leads to good oncological results. Free flap reconstruction has been shown to be a suitable option for extensive defects in aesthetically challenging regions.

Enhanced detection of oral dysplasia by structured illumination fluorescence lifetime imaging microscopy

We demonstrate that structured illumination microscopy has the potential to enhance fluorescence lifetime imaging microscopy (FLIM) as an early detection method for oral squamous cell carcinoma. FLIM can be used to monitor or detect changes in the fluorescence lifetime of metabolic cofactors (e.g. NADH and FAD) associated with the onset of carcinogenesis. However, out of focus fluorescence often interferes with this lifetime measurement. Structured illumination fluorescence lifetime imaging (SI-FLIM) addresses this by providing depth-resolved lifetime measurements, and applied to oral mucosa, can localize the collected signal to the epithelium. In this study, the hamster model of oral carcinogenesis was used to evaluate SI-FLIM in premalignant and malignant oral mucosa. Cheek pouches were imaged in vivo and correlated to histopathological diagnoses. The potential of NADH fluorescence signal and lifetime, as measured by widefield FLIM and SI-FLIM, to differentiate dysplasia (pre-malignancy) from normal tissue was evaluated. ROC analysis was carried out with the task of discriminating between normal tissue and mild dysplasia, when changes in fluorescence characteristics are localized to the epithelium only. The results demonstrate that SI-FLIM (AUC = 0.83) is a significantly better (p-value = 0.031) marker for mild dysplasia when compared to widefield FLIM (AUC = 0.63).

A novel lightweight deep convolutional neural network for early detection of oral cancer

OBJECTIVES

To develop a lightweight deep convolutional neural network (CNN) for binary classification of oral lesions into benign and malignant or potentially malignant using standard real-time clinical images.

METHODS

A small deep CNN, that uses a pretrained EfficientNet-B0 as a lightweight transfer learning model, was proposed. A data set of 716 clinical images was used to train and test the proposed model. Accuracy, specificity, sensitivity, receiver operating characteristics (ROC) and area under curve (AUC) were used to evaluate performance. Bootstrapping with 120 repetitions was used to calculate arithmetic means and 95% confidence intervals (CIs).

RESULTS

The proposed CNN model achieved an accuracy of 85.0% (95% CI: 81.0%-90.0%), a specificity of 84.5% (95% CI: 78.9%-91.5%), a sensitivity of 86.7% (95% CI: 80.4%-93.3%) and an AUC of 0.928 (95% CI: 0.88-0.96).

CONCLUSIONS

Deep CNNs can be an effective method to build low-budget embedded vision devices with limited computation power and memory capacity for diagnosis of oral cancer. Artificial intelligence (AI) can improve the quality and reach of oral cancer screening and early detection.