Oral dysplasia: biomarkers, treatment, and follow-up

Anti-VEGFR2 neutralising antibody slows the progression of multistep oral carcinogenesis

Angiogenesis plays an important role in cancer growth and metastasis, and it is considered a therapeutic target to control tumour growth following anti-angiogenic therapy. However, it is still unclear when tissues initiate angiogenesis during malignant transformation from premalignant condition and whether this premalignant condition could be a therapeutic target of anti-angiogenic therapy. In this study, we aimed to analyse the onset of angiogenesis by evaluating morphological and functional alterations of microvessels during oral multistep carcinogenesis using a 4-nitroquinoline 1-oxide (4NQO)-induced oral carcinogenesis mouse model. In the study, we initially confirmed that with the use of 4NQO, oral lesions develop in a stepwise manner from normal mucosa through oral epithelial dysplasia (OED) to oral squamous cell carcinoma (OSCC). Evaluation of CD31-immunostained specimens revealed that microvessel density (MVD) increases in a stepwise manner from OEDs. Histological and functional analyses revealed the structural abnormalities and leakage of blood vessels had already taken place in OED. Then we evaluated the expression profiles of Hif1a and Vegfa along with hypoxic status and found that OED exhibited increased Vegfa expression under hypoxic conditions. Finally, we tested the possibility of OEDs as a target of anti-angiogenic therapy and found that anti-VEGFR2 neutralising antibody in OED slowed the disease progression from OED to OSCC. These data indicate that an angiogenic switch occurs at the premalignant stage and morphological, and functional alterations of microvessels already exist in OED. These findings also elucidate the tumour microenvironment, which gradually develops along with carcinogenic processes, and highlight usefulness of the 4NQO-induced carcinogenesis model in the study of epithelial and stromal components, which will support epithelial carcinogenesis. © 2024 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

A fully automated and explainable algorithm for predicting malignant transformation in oral epithelial dysplasia

Oral epithelial dysplasia (OED) is a premalignant histopathological diagnosis given to lesions of the oral cavity. Its grading suffers from significant inter-/intra-observer variability, and does not reliably predict malignancy progression, potentially leading to suboptimal treatment decisions. To address this, we developed an artificial intelligence (AI) algorithm, that assigns an Oral Malignant Transformation (OMT) risk score based on the Haematoxylin and Eosin (H&E) stained whole slide images (WSIs). Our AI pipeline leverages an in-house segmentation model to detect and segment both nuclei and epithelium. Subsequently, a shallow neural network utilises interpretable morphological and spatial features, emulating histological markers, to predict progression. We conducted internal cross-validation on our development cohort (Sheffield; n = 193 cases) and independent validation on two external cohorts (Birmingham and Belfast; n = 89 cases). On external validation, the proposed OMTscore achieved an AUROC = 0.75 (Recall = 0.92) in predicting OED progression, outperforming other grading systems (Binary: AUROC = 0.72, Recall = 0.85). Survival analyses showed the prognostic value of our OMTscore (C-index = 0.60, p = 0.02), compared to WHO (C-index = 0.64, p = 0.003) and binary grades (C-index = 0.65, p < 0.001). Nuclear analyses elucidated the presence of peri-epithelial and intra-epithelial lymphocytes in highly predictive patches of transforming cases (p < 0.001). This is the first study to propose a completely automated, explainable, and externally validated algorithm for predicting OED transformation. Our algorithm shows comparable-to-human-level performance, offering a promising solution to the challenges of grading OED in routine clinical practice.

Prognostic biomarkers for malignant progression of oral epithelial dysplasia: an updated systematic review and meta-analysis

Oral epithelial dysplasia (OED) is a premalignant condition that carries an appreciable risk of malignant progression. The current grading system for severity, as defined by the World Health Organization, is a valuable clinical tool, but further work is required to improve the accuracy of predicting OED malignant progression. This systematic review aimed to assess progress in prognostic biomarker discovery in OED over the past 16 years. The primary objective was to update the latest evidence on prognostic biomarkers that may predict malignant progression of OED, with strict inclusion criteria of studies with a longitudinal design and long-term follow-up data to enhance the robustness and translational clinical potential of the findings. Of 2829 studies identified through the searching of five databases, 20 met our inclusion criteria. These studies investigated a total of 32 biomarkers, 20 of which demonstrated significant potential to predict malignant progression of OED. Meta-analysis demonstrated the significant prognostic value of four biomarkers: podoplanin, EGFR expression, p16 methylation, and DNA aneuploidy. Our review has identified 20 reported biomarkers with prognostic potential to predict malignant progression in OED, but their translation into clinical practice remains elusive. Further research is required, and this should focus on validating the promising biomarkers identified in large cohort studies, with adherence to standardised reporting guidelines.

Assessing Oral Epithelial Dysplasia Risk for Transformation to Cancer: Comparison Between Histologic Grading Systems Versus S100A7 Immunohistochemical Signature-based Grading

While a 3-tier oral epithelial dysplasia grading system has been utilized for decades, it is widely recognized as a suboptimal risk indicator for transformation to cancer. A 2-tier grading system has been proposed, although not yet validated. In this study, the 3-tier and 2-tier dysplasia grading systems, and an S100A7 immunohistochemical signature-based grading system were compared to assess prediction of risk of transformation to oral cancer. Formalin-fixed, paraffin-embedded biopsy specimens with known clinical outcomes were obtained retrospectively from a cohort of 48 patients. Hematoxylin and eosin-stained slides were used for the 2- and 3-tier dysplasia grading, while S100A7 for biomarker signature-based assessment was based on immunohistochemistry. Inter-observer variability was determined using Cohen's kappa ( K ) statistic with Cox regression disease free survival analysis used to determine if any of the methods were a predictor of transformation to oral squamous cell carcinoma. Both the 2- and 3-tier dysplasia grading systems ranged from slight to substantial inter-observer agreement ( Kw between 0.093 to 0.624), with neither system a good predictor of transformation to cancer (at least P =0.231; ( P >>>0.05). In contrast, the S100A7 immunohistochemical signature-based grading system showed almost perfect inter-observer agreement ( Kw =0.892) and was a good indicator of transformation to cancer ( P =0.047 and 0.030). The inherent grading challenges with oral epithelial dysplasia grading systems and the lack of meaningful prediction of transformation to carcinoma highlights the significant need for a more objective, quantitative, and reproducible risk assessment tool such as the S100A7 immunohistochemical signature-based system.

Exploring the microbiome of oral epithelial dysplasia as a predictor of malignant progression

A growing body of research associates the oral microbiome and oral cancer. Well-characterized clinical samples with outcome data are required to establish relevant associations between the microbiota and disease. The objective of this study was to characterize the community variations and the functional implications of the microbiome in low-grade oral epithelial dysplasia (OED) using 16S rRNA gene sequencing from annotated archival swabs in progressing (P) and non-progressing (NP) OED. We characterised the microbial community in 90 OED samples - 30 swabs from low-grade OED that progressed to cancer (cases) and 60 swabs from low-grade OED that did not progress after a minimum of 5 years of follow up (matched control subjects). There were small but significant differences between P and NP samples in terms of alpha diversity as well as beta diversity in conjunction with other clinical factors such as age and smoking status for both taxa and functional predictions. Across all samples, the most abundant genus was Streptococcus, followed by Haemophilus, Rothia, and Neisseria. Taxa and predicted functions were identified that were significantly differentially abundant with progression status (all Ps and NPs), when samples were grouped broadly by the number of years between sampling and progression or in specific time to progression for Ps only. However, these differentially abundant features were typically present only at low abundances. For example, Campylobacter was present in slightly higher abundance in Ps (1.72%) than NPs (1.41%) and this difference was significant when Ps were grouped by time to progression. Furthermore, several of the significantly differentially abundant functions were linked to the Campylobacteraceae family in Ps and may justify further investigation. Larger cohort studies to further explore the microbiome as a potential biomarker of risk in OED are warranted.

Oral leukoplakia: A review of clinical features and trends in management

Introduction: Oral potentially malignant disorders (OPMD) conisit of the group of diseases of great importance for dentists. Oral leukoplakia (OL) has long been the subject of debate by numerous researchers. A common etiologic factor is tobacco, which is associated with oral cancer. The aim of the study is to indicate the severity of the lesion, the most common clinical characreistics and localization. The prevalence of leukoplakia in the world is 2.6% with a rate of malignant conversion ranging from 0.1% to 17.5%. Literature data about the prevalence and annual rate of malignant transformation, approximately 2%, indicate that these changes should be taken seriously and regularymonitored Conclusion: Occurate diagnosis provides the key to preventing to malignant transformation. Various medical and surgical treatment modalities for this lesion have been described. This article highlights various trends in the diagnosis and treatment of oral leukoplakia.

Predicting progression of low-grade oral dysplasia using brushing based DNA ploidy and Chromatin Organization analysis

Most oral cancers arise from oral potentially malignant lesions, which show varying grades of dysplasia. Risk of progression increases with increasing grade of dysplasia, however risk prediction among oral low-grade dysplasia (LGDs) i.e., mild and moderate dysplasia can be challenging as only 5-15% transform. Moreover, grading of dysplasia is subjective and varies with the area of the lesion being biopsied. To date, no biomarkers or tools are used clinically to triage oral LGDs. This study utilizes a combination of DNA ploidy and chromatin organization (CO) scores from cells obtained from lesion brushings to identify oral LGDs at high-risk of progression. A total of 130 lesion brushings from patients with oral LGDs were selected of which 16 (12.3%) lesions progressed to severe dysplasia or cancer. DNA ploidy and CO scores were analyzed from nuclear features measured by our in-house DNA image cytometry (DNA-ICM) system and used to classify brushings into low risk and high risk. A total of 57 samples were classified as high-risk of which 13 were progressors. High-risk DNA brushing was significant for progression (P = 0.001) and grade of dysplasia (P = 0.004). Multivariate analysis showed high-risk DNA brushing showed 5.1 to 8-fold increased risk of progression, a stronger predictor than dysplasia grading and lesion clinical features. DNA-ICM can serve as a non-invasive, high throughput tool to identify high-risk lesions several years prior to transformation. This will help clinicians focus on such lesions while low-risk lesions may be spared from unnecessary biopsies.

Predicting the clinical outcome of oral potentially malignant disorders using transcriptomic-based molecular pathology

BACKGROUND

This study was undertaken to develop and validate a gene expression signature that characterises oral potentially malignant disorders (OPMD) with a high risk of undergoing malignant transformation.

METHODS

Patients with oral epithelial dysplasia at one hospital were selected as the 'training set' (n = 56) whilst those at another hospital were selected for the 'test set' (n = 66). RNA was extracted from formalin-fixed paraffin-embedded (FFPE) diagnostic biopsies and analysed using the NanoString nCounter platform. A targeted panel of 42 genes selected on their association with oral carcinogenesis was used to develop a prognostic gene signature. Following data normalisation, uni- and multivariable analysis, as well as prognostic modelling, were employed to develop and validate the gene signature.

RESULTS

A prognostic classifier composed of 11 genes was developed using the training set. The multivariable prognostic model was used to predict patient risk scores in the test set. The prognostic gene signature was an independent predictor of malignant transformation when assessed in the test set, with the high-risk group showing worse prognosis [Hazard ratio = 12.65, p = 0.0003].

CONCLUSIONS

This study demonstrates proof of principle that RNA extracted from FFPE diagnostic biopsies of OPMD, when analysed on the NanoString nCounter platform, can be used to generate a molecular classifier that stratifies the risk of malignant transformation with promising clinical utility.

Loss of FANCD2 and related proteins may predict malignant transformation in oral epithelial dysplasia

OBJECTIVE

Predicting malignant transformation (MT) in oral epithelial dysplasia (OED) is challenging. The higher rate of MT reported in nonsmokers suggests an endogenous etiology in oncogenesis. We hypothesize that loss of FANCD2 and associated proteins could influence genomic instability and MT in the absence of environmental carcinogens.

STUDY DESIGN

Longitudinal archival samples were obtained from 40 individuals with OED: from diagnosis to the most recent review in 23 patients with stable OED or until excision of the squamous cell carcinoma in 17 patients with unstable OED undergoing MT. Histopathological reassessment, immunohistochemistry for FANCD2, and Western blotting for phosphorylation/monoubiquitylation status of ATR, CHK1, FANCD2, and FANCG were undertaken on each tissue sample.

RESULTS

Decreased expression of FANCD2 was observed in the diagnostic biopsies of OED lesions that later underwent MT. Combining the FANCD2 expression scores with histologic grading more accurately predicted MT (P = .005) than histology alone, and it correctly predicted MT in 10 of 17 initial biopsies. Significantly reduced expression of total FANCD2, pFANCD2, pATR, pCHK-1, and pFANCG was observed in unstable OED.

CONCLUSIONS

There is preliminary evidence that defects in the DNA damage sensing/signaling/repair cascade are associated with MT in OED. Loss of expression of FANCD2 protein in association with a higher histologic grade of dysplasia offered better prediction of MT than clinicopathologic parameters alone.

A Wnt-mediated phenotype switch along the epithelial-mesenchymal axis defines resistance and invasion downstream of ionising radiation in oral squamous cell carcinoma

BACKGROUND

Dynamic transitions of tumour cells along the epithelial-mesenchymal axis are important in tumorigenesis, metastasis and therapy resistance.

METHODS

In this study, we have used cell lines, 3D spheroids and tumour samples in a variety of cell biological and transcriptome analyses to highlight the cellular and molecular dynamics of OSCC response to ionising radiation.

RESULTS

Our study demonstrates a prominent hybrid epithelial-mesenchymal state in oral squamous cell carcinoma cells and tumour samples. We have further identified a key role for levels of E-cadherin in stratifying the hybrid cells to compartments with varying levels of radiation response and radiation-induced epithelial-mesenchymal transition. The response to radiation further entailed the generation of a new cell population with low expression levels of E-cadherin, and positive for Vimentin (ECAD^Low/Neg-VIM^Pos), a phenotypic signature that showed an enhanced capacity for radiation resistance and invasion. At the molecular level, transcriptome analysis of spheroids in response to radiation showed an initial burst of misregulation within the first 30 min that further declined, although still highlighting key alterations in gene signatures. Among others, pathway analysis showed an over-representation for the Wnt signalling pathway that was further confirmed to be functionally involved in the generation of ECAD^Low/Neg-VIM^Pos population, acting upstream of radiation resistance and tumour cell invasion.

CONCLUSION

This study highlights the functional significance and complexity of tumour cell remodelling in response to ionising radiation with links to resistance and invasive capacity. An area of less focus in conventional radiotherapy, with the potential to improve treatment outcomes and relapse-free survival.

Recurrence rates after surgical removal of oral leukoplakia-A prospective longitudinal multi-centre study

Oral leukoplakia (OL) is a potentially malignant oral disorder. The Gold Standard treatment is to remove surgically the OL. Despite optimal surgery, the recurrence rates are estimated to be 30%. The reason for this is unknown. The aim of this study was to investigate the clinical factors that correlate with recurrence after surgical removal of OL. In a prospective study data were collected from 226 patients with OL. Forty-six patients were excluded due to incomplete records or concomitant presence of other oral mucosal diseases. Overall, 180 patients proceeded to analysis (94 women and 86 men; mean age, 62 years; age range, 28–92 years). Clinical data, such as gender, diagnosis (homogeneous/non-homogeneous leukoplakia), location, size, tobacco and alcohol use, verified histopathological diagnosis, and clinical photograph, were obtained. In patients who were eligible for surgery, the OL was surgically removed with a margin. To establish recurrence, a healthy mucosa between the surgery and recurrence had to be confirmed in the records or clinical photographs. Statistical analysis was performed with the level of significance set at P<0.05. Of the 180 patients diagnosed with OL, 57% (N = 103) underwent surgical removal in toto. Recurrence was observed in 43 OL. The cumulative incidence of recurrence of OL was 45% after 4 years and 49% after 5 years. Fifty-six percent (N = 23) of the non-homogeneous type recurred. Among snuff-users 73% (N = 8) cases of OL recurred. A non-homogeneous type of OL and the use of snuff were significantly associated with recurrence after surgical excision (P = 0.021 and P = 0.003, respectively). Recurrence was also significantly associated with cancer transformation (P<0.001). No significant differences were found between recurrence and any of the following: dysplasia, site of lesion, size, multiple vs. solitary OL, gender, age, use of alcohol or smoking. In conclusion, clinical factors that predict recurrence of OL are non-homogeneous type and use of snuff.

Oral epithelial dysplasia: Causes, quantification, prognosis, and management challenges

Oral epithelial dysplasia is a spectrum of architectural and cytological epithelial changes caused by accumulation of genetic changes, and is associated with an increased risk of progression to squamous cell carcinoma. It is a microscopic diagnosis of immense clinical importance. The initial reports of oral potentially malignant disorders with oral epithelial dysplasia transforming to oral cancer helped in understanding the nature of oral malignancies. Since then, clinical studies on oral potentially malignant disorders have combined microscopic findings of oral epithelial dysplasia to assess the malignant transformation potential of different grades of epithelial dysplasia. A significant amount of scientific literature has amassed on oral epithelial dysplasia relating to aspects of its diagnosis and management. However, the evidence base is weak as a result of the significant variability of published research. Poorly described study methods, variability in different oral epithelial dysplasia grading systems, inter- and intra-examiner variability causing issues of reliability, inadequate sample size, and inconsistent durations of follow-up are some of the methodological issues contributing to the failure to provide dependable information. Randomized clinical trials on the malignant transformation potential of oral epithelial dysplasia and its treatment outcomes are limited. This comprehensive literature review on oral epithelial dysplasia summarizes the scientific knowledge published in the scientific literature in English since its first description. The historical development, etiological factors, grading systems, diagnostic criteria, assessment of risk factors and prevention of malignant transformation, management principles of different grades of oral epithelial dysplasia (surgical and nonsurgical), recommendations on follow-up, and prognostic indicators are discussed in detail.

Autofluorescence Imaging to Monitor the Progression of Oral Potentially Malignant Disorders

Patients with oral potentially malignant disorders (OPMD) must undergo regular clinical surveillance to ensure that any progression to malignancy is detected promptly. Autofluorescence imaging (AFI) is an optical modality that can assist clinicians in detecting early cancers and high-grade dysplasia. Patients with OPMD undergoing surveillance for the development of oral cancer were examined using AFI at successive clinic visits. Autofluorescence images acquired at 133 clinical visits from sites in 15 patients who met inclusion criteria were analyzed quantitatively using an algorithm to calculate the red-to-green pixel intensity (RG ratio). A quantitative AFI threshold for high risk of progression was defined based on the RG ratio and was compared with expert clinical impression and with histopathology when available. Patients were divided into two groups based on their endpoint: surveillance (n = 6) or surgery (n = 9). In the surveillance group, 0 of 6 (0%) of patients were clinically identified as high risk for progression prior to the study endpoint, whereas 1 of 6 (17%) of patients were deemed at high risk for progression based on AFI during the same time period. In the surgery group, 9 of 9 (100%) of patients were clinically identified as high risk prior to the study endpoint, whereas 8 of 9 (89%) of patients were at high risk for progression based on AFI during the same time period. AFI results tracked over time were comparable with expert clinical impression in these patient groups. AFI has the potential to aid clinicians in noninvasively monitoring oral precancer and evaluating OPMDs that require increased surveillance.

Meta-analysis of the predictive value of DNA aneuploidy in malignant transformation of oral potentially malignant disorders

DNA aneuploidy is an imbalance of chromosomal DNA content that has been highlighted as a predictor of biological behavior and risk of malignant transformation. To date, DNA aneuploidy in oral potentially malignant diseases (OPMD) has been shown to correlate strongly with severe dysplasia and high-risk lesions that appeared non-dysplastic can be identified by ploidy analysis. Nevertheless, the prognostic value of DNA aneuploidy in predicting malignant transformation of OPMD remains to be validated. The aim of this meta-analysis was to assess the role of DNA aneuploidy in predicting malignant transformation in OPMD. The questions addressed were (i) Is DNA aneuploidy a useful marker to predict malignant transformation in OPMD? (ii) Is DNA diploidy a useful negative marker of malignant transformation in OPMD? These questions were addressed using the PECO method. Five studies assessing aneuploidy as a risk marker of malignant change were pooled into the meta-analysis. Aneuploidy was found to be associated with a 3.12-fold increased risk to progress into cancer (RR=3.12, 95% CI 1.86-5.24). Based on the five studies meta-analyzed, "no malignant progression" was more likely to occur in DNA diploid OPMD by 82% when compared to aneuploidy (RR=0.18, 95% CI 0.08-0.41). In conclusion, aneuploidy is a useful marker of malignant transformation in OPMD, although a diploid result should be interpreted with caution.

Oral malignancy and premalignancy

This article increases awareness of the presentation, diagnosis and management of potentially malignant and malignant oral lesions and conditions and reviews the referral process.

Photodynamic therapy: a review and its prospective role in the management of oral potentially malignant disorders

With the unreliability of epithelial dysplasia as a predictor to determine the risk of future malignant development, subjectivity associated in evaluating dysplasia by pathologists and paucity of biomarkers that could accurately predict the progression risks in oral potentially malignant disorders (PMDs), eradication of the lesions appears to be the most desirable approach to minimize the risk of invasive cancer formation. Interventions, such as surgery and chemoprevention, have not shown promising long-term results in the treatment of these lesions, and lack of guidelines and general consensus on their management has incited much anxiety and doubts in both patients and community clinicians. Topical photodynamic therapy (PDT) is a minimally invasive and minimally toxic technique that in recent years has shown great promise in the management of PMDs. In this review, we describe the historical developments in the field of PDT, its basic mechanisms, as well as related clinical studies, and its challenges in the management of oral PMDs. Based on its high efficacy and low side effects, its high patient acceptance/compliance, the simplicity of the procedure and its minimal pretreatment preparation, topical PDT is believed to have potential to play an important role in the management of PMDs, especially of the low-grade dysplasia.

Tetraspanins CD9 and CD151, epidermal growth factor receptor and cyclooxygenase-2 expression predict malignant progression in oral epithelial dysplasia

Background:

Prognostic biomarkers aim to improve on the current inadequate method of histological assessment to identify patients with oral epithelial dysplasia at greatest risk of malignant transformation. We aimed to assess the prognostic ability of six protein biomarkers linked to the epidermal growth factor receptor (EGFR) pathway, including three tetraspanins, in a large multicentre oral dysplasia cohort.

Methods:

One hundred and forty-eight cases with varying degrees of epithelial dysplasia underwent immunohistochemical assessment for CD9, CD151, CD82, EGFR, Her-2, and COX-2. Scoring was performed independently by two observers. Univariate analyses using both logistic and Cox regression models and a multivariate regression were performed.

Results:

Malignant progression was significantly greater in those cases with decreased expression of CD9 (P=0.02), and increased expression of CD151 (P=0.02), EGFR (P=0.04), and COX-2 (P=0.003). Histological grade (P=0.0002) and morphology (P=0.03) were also prognostic, whereas smoking and alcohol were not. The optimal combination by backward-variable selection was of histological grade (hazard ratio (HR) 1.64; 95% CI 1.12, 2.40), COX-2 overexpression (HR 1.12; 1.02, 1.24) and CD9 underexpression (HR 0.88; 0.80, 0.97). CD82 and Her-2 demonstrated no prognostic ability.

Conclusion:

This is the first study of the expression and prognostic potential of the tetraspanins in oral dysplasia. A combination of certain biomarkers with clinical factors appeared to improve the accuracy of determining the risk of malignancy in individuals with oral dysplasia. These findings may also offer potential new therapeutic approaches for this condition.

S100A7 overexpression is a predictive marker for high risk of malignant transformation in oral dysplasia

Early detection of oral lesions (OLs) at high risk of cancer development is of utmost importance for intervention. There is an urgent unmet clinical need for biomarkers that allow identification of high-risk OLs. Recently, we identified and verified a panel of five candidate protein biomarkers namely S100A7, prothymosin alpha, 14-3-3ζ, 14-3-3σ and heterogeneous nuclear ribonucleoprotein K using proteomics to distinguish OLs with dysplasia and oral cancers from normal oral tissues. The objective of our study was to evaluate the potential of these candidate protein biomarkers for identification of oral dysplastic lesions at high risk of cancer development. Using immunohistochemistry, we analyzed expressions of these five candidate protein biomarkers in 110 patients with biopsy-proven oral dysplasia and known clinical outcome and determined their correlations with p16 expression and HPV 16/18 status. Kaplan-Meier survival analysis showed reduced oral cancer-free survival (OCFS) of 68.6 months (p = 0.007) in patients showing cytoplasmic S100A7 overexpression when compared to patients with weak or no S100A7 immunostaining in cytoplasm (mean OCFS = 122.8 months). Multivariate Cox regression analysis revealed cytoplasmic S100A7 overexpression as the most significant candidate marker associated with cancer development in dysplastic lesions (p = 0.041, hazard ratio = 2.36). In conclusion, our study suggested the potential of S100A7 overexpression in identifying OLs with dysplasia at high risk of cancer development.

Oral premalignancy: the roles of early detection and chemoprevention

Premalignancy and chemoprevention studies in head and neck cancer typically focus on the oral cavity. Avoiding or cessation of alcohol and smoking, early detection of potentially malignant disorders or cancer, and early detection of recurrent and/or second primary tumor form the basis of prevention of oral cancer. Analysis of tissue prospectively collected in evaluation of retinoids for chemoprevention trials allowed identification of molecular biomarkers of risk to develop oral cancer, loss of heterozygosity being the most validated one. Improving risk assessment and identification of new targets for chemoprevention represent the main challenges in this field.

Chromosomal instability, aneuploidy and routine high-resolution DNA content analysis in oral cancer risk evaluation

Carcinogen exposure of the oral cavity is thought to create an extensive 'field cancerization'. According to this model, a very early precursor of oral cancer is a patch of normal-appearing mucosa in which stem cells share genetic/genomic aberrations. These precancerous fields then become clinically visible as white and red lesions (leuko- and erythro-plakias), which represent the vast majority of the oral potentially malignant disorders. This review focuses on aneuploidy (where it is from) and on biomarkers associated with DNA aneuploidy in oral mucosa and oral potentially malignant disorders, as detected by DNA image and flow cytometry. Data from the literature strongly support the association of DNA ploidy with dysplasia. However, work is still needed to prove the clinical value of DNA ploidy in large-scale prospective studies. Using high-resolution DNA flow cytometry with fresh/frozen material and the degree of DNA aneuploidy (DNA Index) might improve the prediction of risk of oral cancer development.

In vivo layer-resolved characterization of oral dysplasia via nonlinear optical micro-spectroscopy

Optical spectroscopy has proven to be a powerful technique for studying neoplastic transformation in epithelial tissue. Since specific intra-layer precancerous changes originate in the stratified layers of the oral mucosa, layer-resolved analysis will likely improve both our understanding of the mechanism of premalignant transformation, and clinical diagnostic outcomes. However, the native fluorescence signal in linear spectroscopy typically originates from a multi-layered focal volume. In this study, nonlinear spectroscopy was exploited for in vivo layer-resolved discrimination between normal and dysplastic tissue for the first time. Our results revealed numerous intra-layer specific differences.

Feasibility of recruitment to an oral dysplasia trial in the United Kingdom

Background

Oral epithelial dysplasia (OED) has a malignant potential. Therapeutic options for OED remain both limited and without good evidence. Despite surgery being the most common method of treating OED, recurrence and potentially significant morbidity remain problematic. Consequently, there has been much interest in non-surgical treatments for OED. Cyclo-oxygenase (COX) up-regulation is known to occur in the dysplasia-carcinoma sequence and evidence now exists that COX-2 is a prognostic marker of malignant transformation in OED. COX-inhibitors are therefore considered a potential therapeutic strategy for treating this condition. We aimed to provide both proof of principal evidence supporting the effect of topical COX inhibition, and determine the feasibility of recruitment to an OED chemoprevention trial in the UK.

Methods

Recruitment of 40 patients with oral leukoplakia to 4 study arms was planned. The total daily dose of Aspirin would increase in each group and be used in the period between initial diagnostic and follow-up biopsies.

Results

During the 15-month recruitment period, 15/50 screened patients were eligible for recruitment, and 13 (87%) consented. Only 1 had OED diagnosed on biopsy. 16 patients were intolerant of, or already taking Aspirin and 16 patients required no biopsy. Initial recruitment was slow, as detection relied on clinicians identifying potentially eligible patients. Pre-screening new patient letters and directly contacting patients listed for biopsies improved screening of potentially eligible patients. However, as the incidence of OED was so low, it had little impact on trial recruitment. The trial was terminated, as recruitment was unlikely to be achieved in a single centre.

Conclusion

This feasibility trial has demonstrated the low incidence of OED in the UK and the difficulties in conducting a study because of this. With an incidence of around 1.5/100,000/year and a high proportion of those patients already taking or intolerant of Aspirin, a large multi-centred trial would be required to fulfil the recruitment for this study. The ability of topical non-steroidal anti-inflammatory drugs to modify COX and prostaglandin expression remains an important but unanswered question. Collaboration with centres in other parts of the world with higher incidences of the disease may be required to ensure adequate recruitment.

ISRCTN

31503555.

Loss of DLC1 is an independent prognostic factor in patients with oral squamous cell carcinoma

Deleted in liver cancer (DLC1), a Rho GTPase-activating protein, was observed to be differentially expressed in oral squamous cell carcinoma in comparison with normal tissues using tissue proteomics. In the current study, we investigated the clinical significance of loss of DLC1 expression in different stages of development of oral squamous cell carcinoma to determine its potential as a biomarker for oral dysplasia and prognosis of oral squamous cell carcinoma. Immunohistochemical analysis of DLC1 expression was carried out in oral squamous cell carcinoma patients (n=214), dysplasia (n=51), hyperplastic squamous mucosa (n=45), and histologically normal oral tissues (n=80), and correlated with clinicopathological parameters and disease prognosis over 91 months for oral squamous cell carcinomas. Loss of DLC1 expression was observed in oral squamous cell carcinoma (64%), oral dysplasia (31%), hyperplastic squamous mucosa (22%), and normal mucosa (16%). Significant loss of DLC1 expression was observed in oral squamous cell carcinomas as compared with dysplasia (P<0.001, odds ratio=3.8, 95% CI=2.0-7.3), suggesting it may be an important event involved in cancer progression. Among oral squamous cell carcinomas, the loss of DLC1 expression was significantly associated with poor prognosis (P=0.021, hazards ratio (HR)=1.8, 95% CI=1.1-2.9). Multivariate analysis revealed loss of DLC1 (P=0.023, HR=2.1, 95% CI=1.2-3.9) and histopathological grade (P=0.015, HR=1.7, 95% CI=1.1-2.7) to be independent predictors for disease-free survival in oral squamous cell carcinoma patients in comparison with known prognostic factors, viz. tumor stage, nodal status, and overall stage. Loss of DLC1 expression emerged as an important biomarker for predicting patients diagnosed with oral dysplasia at high risk of transformation upon future validation in longitudinal studies. Loss of DLC1 expression is a poor prognostic marker for oral squamous cell carcinoma patients.