Prognosis of oral pre-malignant lesions: significance of clinical, histopathological, and molecular biological characteristics

Factors affecting carbon dioxide laser treatment for oral precancer: a patient cohort study

BACKGROUND

Although the benefits of CO(2) laser surgery in oral precancer management have been evaluated, little consideration has been given to the factors which may influence treatment outcome, especially amongst patients developing recurrence or malignant transformation.

STUDY DESIGN

Seventy eight patients (51 males, 27 females; mean age 57.8 years) undergoing CO(2) laser excision of single, new dysplastic oral precancer lesions (OPLs) were followed up for a minimum of 2 years and the influence of clinico-pathological parameters, socio-demographic factors and the presence or absence of residual dysplasia in excision margins upon clinical outcome were examined.

RESULTS

Seventy three percent of patients were smokers and 78% consumed alcohol regularly. The majority of lesions were leukoplakias arising in the floor of mouth and ventro-lateral tongue and moderate or severe dysplasia accounted for 86% of histopathological diagnoses. Patient follow up ranged from 24 to 119 months (mean 58 months). Sixty four percent of patients were disease free at most recent clinical follow up, whilst 32% developed local recurrent dysplasia or new site dysplasia with 4% developing oral squamous cell carcinoma (but at sites distinct from their initial OPL). Excision margins were clear in 55% of cases, but 19% showed mild, 21% moderate and 5% severe dysplasia on histopathological examination. No statistically significant associations were seen between patients' age, gender, lesion appearance, site of origin, histopathological grading, presence of dysplasia in resection margins, or alcohol consumption and clinical outcome. Smokers, however, were at significantly higher risk of dysplasia recurrence compared to ex-smokers or non-smokers (P = 0.04).

CONCLUSIONS

In the absence of agreed treatment protocols for OPLs, we recommend CO(2) laser surgery as an effective treatment modality offering precise lesion excision, full histopathological assessment, minimal post-operative morbidity and a 64% disease free clinical outcome. Regular patient follow up is encouraged due to the persistence of field cancerisation effects.

Molecular biology: an early detector of oral cancers

Oral cancers have been one of the leading causes of deaths particularly in the developing countries. Prime reason for this high mortality and morbidity is attributed to the delay in diagnosis and prompt treatment. Relentless research in the field of oncology has led to advent of novel procedures for the early detection of oral cancers. Molecular biology is highly promising in this regard. It is a procedure that detects alterations at a molecular level much before they are seen under a microscope and much before clinical changes occur. Molecular studies serve as basis by which we will eventually be able not only to augment clinical assessment and classification of oral lesions but also predict malignant potential of oral lesions, thus reducing incidence and increasing the scope for early diagnosis and treatment of oral cancers. However, making such sophisticated tools available for the common man in developing countries is one of the most important challenges faced today.

DNA aneuploidy and dysplasia in oral potentially malignant disorders: association with cigarette smoking and site

To date there are still no reliable biomarkers for oral potentially malignant disorders (PMDs) to predict the risk of progression to squamous cell carcinoma (SCC). Within a prospective clinical trial of patients with PMDs, DNA content flow cytometry (DNA FCM) was evaluated for 60 PMDs using fresh samples obtained by a dermatological curette. There were 6/42 PMDs without dysplasia, but with DNA aneuploidy, versus 8/18 with both dysplasia and aneuploidy (p=0.02). When the tongue and the buccal mucosa, the two most common sites in the present series of cases were compared, dysplastic PMDs were mainly located on the tongue (p=0.01). Tobacco smokers, who preferentially developed PMDs in the buccal mucosa at a younger age than non-smokers (p=0.002), had fewer dysplastic PMDs than did non-smokers (p=0.01). Dysplasia was significantly linked to DNA aneuploidy (p=0.03) in smokers. The present data suggest that aneuploidy is an early event in oral carcinogenesis and that the influence of tobacco varies according to subsite and patient age. When DNA FCM of PMD samples are obtained by curette scraping, extensive areas can be covered with a minimally invasive, rapid, inexpensive procedure. Moreover DNA FCM of these samples appears easy amenable to routine analysis. Further research on larger numbers of PMDs should be carried out to determine whether DNA FCM plays a role in the prediction of risk of PMD transformation.

Grading systems in head and neck dysplasia: their prognostic value, weaknesses and utility

BACKGROUND

Grading of dysplasia, including head and neck lesions, continues to be a hotly debated subject. It is subjective and lacks intra- and inter-observer reproducibility due to the insufficiency of validated morphological criteria and the biological nature of dysplasia. Moreover, due to the absence of a consensus, several systems are currently employed.

OBJECTIVES

The aims of this review are to: 1) Highlight the significance of dysplasia and the importance of a valid method for assessing precursor lesions of the head and neck. 2) Review the different histopathological classification systems for grading intraepithelial lesions of the head and neck. 3) Discuss and review quality requirements for these grading systems.

CONCLUSION

Regarding the different classification systems, data concerning the WHO classification system are the most available in current literature. There is no simple relationship or overlapping between the classification systems. Further studies should be done to see whether other systems have advantages above the current WHO system and to discover indications that could lead to an universal classification system for intraepithelial lesions of the head and neck.

Activation of P2X(7)-mediated apoptosis Inhibits DMBA/TPA-induced formation of skin papillomas and cancer in mice

BACKGROUND

The study tested the hypothesis that apoptosis can prevent and control growth of neoplastic cells. Previous studies in-vitro have shown that the pro-apoptotic P2X(7) receptor regulates growth of epithelial cells. The specific objective of the present study was to understand to what degree the P2X(7) system controls development and growth of skin cancer in vivo, and what cellular and molecular mechanisms are involved in the P2X(7) action.

METHODS

Skin neoplasias in mice (papillomas, followed by squamous spindle-cell carcinomas) were induced by local application of DMBA/TPA. Experiments in-vitro utilized cultured epidermal keratinocytes generated from wild-type or from P2X(7)-null mice. Assays involved protein immunostaining and Western blots; mRNA real-time qPCR; and apoptosis (evaluated in situ by TUNEL and quantified in cultured keratinocytes as solubilized DNA or by ELISA). Changes in cytosolic calcium or in ethidium bromide influx (P2X(7) pore formation) were determined by confocal laser microscopy.

RESULTS

(a) Co-application on the skin of the P2X7 specific agonist BzATP inhibited formation of DMBA/TPA-induced skin papillomas and carcinomas. At the completion of study (week 28) the proportion of living animals with cancers in the DMBA/TPA group was 100% compared to 43% in the DMBA/TPA+BzATP group. (b) In the normal skin BzATP affected mainly P2X(7)-receptor - expressing proliferating keratinocytes, where it augmented apoptosis without evoking inflammatory changes. (c) In BzATP-treated mice the degree of apoptosis was lesser in cancer than in normal or papilloma keratinocytes. (d) Levels of P2X(7) receptor, protein and mRNA were 4-5 fold lower in cancer tissues than in normal mouse tissues. (e) In cultured mouse keratinocytes BzATP induced apoptosis, formation of pores in the plasma membrane, and facilitated prolonged calcium influx. (f) The BzATP-induced apoptosis, pore-formation and augmented calcium influx had similar dose-dependence for BzATP. (g) Pore formation and the augmented calcium influx were depended on the expression of the P2X(7) receptor, while the BzATP-induced apoptosis depended on calcium influx. (h) The BzATP-induced apoptosis could be blocked by co-treatment with inhibitors of caspase-9 and caspase-3, but not of caspase-8.

CONCLUSION

(a) P2X(7)-dependent apoptosis is an important mechanism that controls the development and progression of epidermal neoplasia in the mouse. (b) The P2X(7)-dependent apoptosis is mediated by calcium influx via P2X(7) pores, and involves the caspase-9 (mitochondrial) pathway. (c) The diminished pro-apoptotic effect of BzATP in mouse cancer keratinocytes is possibly the result of low expression of the P2X(7) receptor. (d) Activation of P2X(7)-dependent apoptosis, e.g. with BzATP could be a novel chemotherapeutic growth-preventive modality for papillomas and epithelial cancers in vivo.

Oral Erythroplakia and Speckled Leukoplakia: retrospective analysis of 13 cases

Erythroplakia and speckled leukoplakia are oral precancerous lesions that have a high potential for malignant transformation.

Aim

A retrospective analysis was conducted to investigate the clinicopathologic features of 13 cases of oral erythroplakia and speckled leukoplakia in patients who were seen at a center specialized in stomatology and Histopathological diagnosis of oral diseases.

Materials and Methods

All cases diagnosed with erythroplakia and speckled leukoplakia between 1978 and 2006 were retrieved from the service archives.

Results

The lesions exhibited a predilection for males with a female-to-male ratio of 1:3.3. Mean age was 57 years old and soft palate was the site affected in 77% of the cases. Pain symptoms were reported by 61.5% of the patients and association with risk factors such as smoking and excessive alcohol intake was seen in 100% and in 46% of the cases, respectively. The lesions showed epithelial dysplasia, where more than 50% were diagnosed as in situ or invasive carcinoma.

Conclusions

Despite low prevalence, oral homogeneous erythroplakia and speckled leukoplakia show Histopathological alterations vary from epithelial dysplasia to invasive carcinoma. These lesions must be included among those oral lesions with the highest potential for malignant tranformation.

Histological changes in intra-oral skin flaps

This review outlines the histological features of intra-oral skin flaps and their pathology as encountered in a routine head and neck diagnostic histopathology service. Problems in recognising and interpreting unfamiliar and complex appearances, and areas of diagnostic and prognostic uncertainty, are highlighted.

DNA copy number variation and loss of heterozygosity in relation to recurrence of and survival from head and neck squamous cell carcinoma: a review

Genetic aberrations, such as DNA copy number variation (CNV) and loss of heterozygosity (LOH), have been implicated in head and neck squamous cell carcinoma (HNSCC) initiation and progression. This review examines CNV and LOH as predictors of HNSCC recurrence and mortality. We searched PubMed for relevant publications and compared and discussed results from the articles. Certain CNV and LOH events have consistently been associated with HNSCC recurrence and survival. The recent high-resolution single nucleotide polymorphism (SNP) arrays have the potential to identify many more genetic changes and concurrent genome-wide CNV, copy-neutral and/or allelic imbalance LOH in HNSCC that may bear on prognosis. Our review confirms that outcome in HNSCC can be predicted to a considerable extent by the presence of tumor cell genetic aberrations. It points out the limitations of some methodologies that were used in the past and discusses the advantages and challenges of using genome-wide SNP arrays.

Factors Affecting the Referral of Potentially Malignant Lesions from Primary Dental Care: A Pilot Study in South Yorkshire

Aims

Early diagnosis of oral cancer is an essential element of prevention, yet many patients present late, suggesting that criteria used for referral miss the small or early-stage lesions. The aims of this study were to determine what cues are used by primary care dentists when making the decision to refer a suspicious lesion, and to investigate their recent referral behaviour.

Methods

A cross-sectional study using a postal questionnaire was undertaken in a major conurbation in South Yorkshire. The questionnaire was sent to all 95 practices in the area concerned. Primary care dentists were asked to score a range of cues on a five-point scale and list their top ten. Experience of referrals made in the last 12 months was also recorded.

Results

Forty-two questionnaires were returned (44.2%). The cues that primary care dentists ‘agreed’ or ‘strongly agreed’ would initiate a referral were: ‘fixed’, ‘smokes >20 cigarettes/day’, ‘indurated’, ‘ragged borders’ and ‘ulceration’. The most cited top-ten cues were ‘ulcerated’, ‘fixed to underlying tissues’, ‘smoking’ and ‘indurated’. The median number of lesions referred was 0.77 per 1000 adult patients. Twenty-six dentists recorded their experience of 29 lesions. Of these, 17% had been found by the patient whereas 80% had been found at a routine dental examination. Seventy-nine per cent had been present for more than six weeks. Reasons for referral included atypical appearance (38%), ulceration (21%) and location (21%). Fifty-four per cent of primary care dentists described their relationship with secondary care as either ‘good’ or ‘excellent’.

Conclusions

The most cited cues related to established or advanced disease, not to ‘red’ and ‘white’ lesions, which the National Institute for Health and Clinical Excellence (NICE) recommend for early referral. Even allowing for the relatively poor response rate, this suggests that some small lesions of oral cancer are being missed.

1H NMR-based metabonomic and pattern recognition analysis for detection of oral squamous cell carcinoma

BACKGROUND

Metabonomic analysis has been increasingly used to monitor metabolic abnormalities in cells and their microenvironment in order to detect the cancer markers recently. We evaluated the feasibility of applying (1)H nuclear magnetic resonance ((1)H NMR) based metabonomic method in the early detection of the differences in the plasma from 3 groups, which were patients with oral squamous cell carcinoma (OSCC), patients with oral leukoplakia (OLK), and the healthy control group.

METHODS

(1)H NMR spectra were obtained from human plasma samples prior to spectral analysis. The obtained data were processed by both the unsupervised principal component analysis (PCA) and the supervised partial least squares discriminant analysis (PLS-DA) to find out the differences among the three groups.

RESULTS

PLS-DA analysis has revealed a good model to detect the NMR data that can differentiate the OSCC patients from the OLK patients and the controls using a test set.

CONCLUSION

The results indicated that the (1)H NMR-based metabonomic approach is a feasible and efficient method for differentiating the OSCC patient's plasma from the healthy controls. As a potential novel strategy and a more convenient technique, it deserves a further evaluation for an early detection of oral cancer.

Isolation and characterization of an immortalized oral keratinocyte cell line of mouse origin

OBJECTIVE

To establish an oral epithelial cell line of mouse origin for molecular and biochemical assays.

DESIGN

Epithelial cells were isolated from the oral cavity of adult mice and established as a spontaneously immortalized cell line in culture, designated immortalized oral keratinocyte cells (IMOK cells). The cells were then characterized for growth characteristics, differentiation potential, karyotype, transfectability, susceptibility to viral infection and responses to siRNA.

RESULTS

The IMOK cells exhibit robust growth in both serum-containing and serum-free medium for at least 100 population doublings. IMOK cells have a near diploid karyotype, express keratinocyte marker proteins and can be induced to undergo differentiation by the addition of high levels of calcium to the medium. The differentiation process is characterized by morphological changes and by the induction of oral epithelium specific differentiation marker proteins such as K4 and K13. Transient transfection analyses reveal that IMOK cells are highly transfectable and that several promoters of epithelial cells are active in these cells. Moreover, upon differentiation with calcium, there is an up-regulation of differentiation-specific K4 and Elf5 promoter activity. Finally, we show that the oral keratinocytes are also amenable to infection with retroviruses and to siRNA-based knockdown of gene expression.

CONCLUSIONS

Our study is the first to establish an immortalized oral keratinocyte cell line of murine origin that can recapitulate the oral epithelium differentiation program and thus could serve as a useful tool for toxicological and molecular analyses of the oral tissue.

Head and neck cancer in the betel quid chewing area: recent advances in molecular carcinogenesis

Head and neck cancer (HNC) is one of the 10 most frequent cancers worldwide, with an estimated over 500,000 new cases being diagnosed annually. The overall 5-year survival rate in patients with HNC is one of the lowest among common malignant neoplasms and has not significantly changed during the last two decades. Oral cavity squamous cell carcinoma (OSCC) shares part of HNC and has been reported to be increasing in the betel quid chewing area in recent years. During 2006, OSCC has become the sixth most common type of cancer in Taiwan, and it is also the fourth most common type of cancer among men. It follows that this type of cancer wreaks a high social and personal cost. Environmental carcinogens such as betel quid chewing, tobacco smoking and alcohol drinking have been identified as major risk factors for head and neck cancer. There is growing interest in understanding the relationship between genetic susceptibility and the prevalent environmental carcinogens for HNC prevention. Within this review, we discuss the molecular and cellular aspects of HNC carcinogenesis in Taiwan, an endemic betel quid chewing area. Knowledge of molecular carcinogenesis of HNC may provide critical clues for diagnosis, prognosis, individualization of therapy and molecular therapeutics.

Gene expression profiling identifies genes predictive of oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is associated with substantial mortality and morbidity. To identify potential biomarkers for the early detection of invasive OSCC, we compared the gene expressions of incident primary OSCC, oral dysplasia, and clinically normal oral tissue from surgical patients without head and neck cancer or preneoplastic oral lesions (controls), using Affymetrix U133 2.0 Plus arrays. We identified 131 differentially expressed probe sets using a training set of 119 OSCC patients and 35 controls. Forward and stepwise logistic regression analyses identified 10 successive combinations of genes which expression differentiated OSCC from controls. The best model included LAMC2, encoding laminin-gamma2 chain, and COL4A1, encoding collagen, type IV alpha1 chain. Subsequent modeling without these two markers showed that COL1A1, encoding collagen, type I alpha1 chain, and PADI1, encoding peptidyl arginine deiminase, type 1, could also distinguish OSCC from controls. We validated these two models using an internal independent testing set of 48 invasive OSCC and 10 controls and an external testing set of 42 head and neck squamous cell carcinoma cases and 14 controls (GEO GSE6791), with sensitivity and specificity above 95%. These two models were also able to distinguish dysplasia (n = 17) from control (n = 35) tissue. Differential expression of these four genes was confirmed by quantitative reverse transcription-PCR. If confirmed in larger studies, the proposed models may hold promise for monitoring local recurrence at surgical margins and the development of second primary oral cancer in patients with OSCC.

The application of normal, SV40 T-antigen-immortalised and tumour-derived oral keratinocytes, under serum-free conditions, to the study of the probability of cancer progression as a result of environmental exposure to chemicals

In vitro models are currently not considered to be suitable replacements for animals in experiments to assess the multiple factors that underlie the development of cancer as a result of environmental exposure to chemicals. An evaluation was conducted on the potential use of normal keratinocytes, the SV40 T-antigen-immortalised keratinocyte cell line, SVpgC2a, and the carcinoma cell line, SqCC/Y1, alone and in combination, and under standardised serum-free culture conditions, to study oral cancer progression. In addition, features considered to be central to cancer development as a result of environmental exposure to chemicals, were analysed. Genomic expression, and enzymatic and functional data from the cell lines reflected many aspects of the transition of normal tissue epithelium, via dysplasia, to full malignancy. The composite cell line model develops aberrances in proliferation, terminal differentiation and apoptosis, in a similar manner to oral cancer progression in vivo. Transcript and protein profiling links aberrations in multiple gene ontologies, molecular networks and tumour biomarker genes (some proposed previously, and some new) in oral carcinoma development. Typical specific changes include the loss of tumour-suppressor p53 function and of sensitivity to retinoids. Environmental agents associated with the aetiology of oral cancer differ in their requirements for metabolic activation, and cause toxic effects to cells in both the normal and the transformed states. The results suggest that the model might be useful for studies on the sensitivity of cells to chemicals at different stages of cancer progression, including many aspects of the integrated roles of cytotoxicity and genotoxicity. Overall, the properties of the SVpgC2a and SqCC/Y1 cell lines, relative to normal epithelial cells in monolayer or organotypic culture, support their potential applicability to mechanistic studies on cancer risk factors, including, in particular, the definition of critical toxicity effects and dose-effect relationships.

Activated checkpoint kinase 2 expression and risk for oral squamous cell carcinoma

BACKGROUND

Phosphoactivation of a DNA damage response molecule checkpoint kinase 2 (pChk2) may be a marker of oral epithelial cells that have entered the precancerous and squamous cell carcinoma (SCC) stages. We explored whether there was selective expression of pChk2 in precancerous lesions but not in nonneoplastic tissue of the oral mucosa.

EXPERIMENTAL DESIGN

In a retrospective cohort design, 96 biopsied clinical leukoplakias and erythroplakias with known subsequent progression to SCC were identified from 48 subjects and assigned as the cases group. Expression status of pChk2 was compared with that of the 97 leukoplakias and erythroplakias that did not progress to SCC (control groups) by immunohistochemical analysis. Included in both groups were lesions with histologically confirmed dysplasia and those that lacked histologic evidence of atypia.

RESULTS

Subjects with pChk2-positive but histology-negative (for atypia) lesions had an 8.6 times higher risk of developing SCC compared with those with pChk2-negative and histology-negative lesions. Overall, the presence of detectable pChk2 staining was able to identify lesions at risk of developing SCC within 3 years with a sensitivity of 85.2%, specificity of 74.2%, and predictive accuracy of 78.2% (odds ratio, 19.9; 95% confidence interval, 7.3-55.5).

CONCLUSION

This is the first study to include histologically nonatypical cases in the analysis of a putative biomarker for oral precancerous lesions. Our data show that pChk2 merits further investigation as a promising biomarker that can discriminate those lesions at risk for developing SCC, regardless of histologic evidence for atypia.

Probing local tissue changes in the oral cavity for early detection of cancer using oblique polarized reflectance spectroscopy: a pilot clinical trial

We report the results of an oral cavity pilot clinical trial to detect early precancer and cancer using a fiber optic probe with obliquely oriented collection fibers that preferentially probe local tissue morphology and heterogeneity using oblique polarized reflectance spectroscopy (OPRS). We extract epithelial cell nuclear sizes and 10 spectral features. These features are analyzed independently and in combination to assess the best metrics for separation of diagnostic classes. Without stratifying the data according to anatomical location or level of keratinization, OPRS is found to be sensitive to four diagnostic categories: normal, benign, mild dysplasia, high-grade dysplasia, and carcinoma. Using linear discriminant analysis, separation of normal from high-grade dysplasia and carcinoma yield a sensitivity and specificity of 90 and 86%, respectively. Discrimination of morphologically similar lesions such as normal from mild dysplasia is achieved with a sensitivity of 75% and specificity of 73%. Separation of visually indistinguishable benign lesions from high-grade dysplasia and carcinoma is achieved with good sensitivity (100%) and specificity (85%), while separation of benign from mild dysplasia gives a sensitivity of 92% and a specificity of 69%. These promising results suggest that OPRS has the potential to aid screening and diagnosis of oral precancer and cancer.

A survey of the current approaches to diagnosis and management of oral premalignant lesions

BACKGROUND

Early diagnosis of oral premalignant lesions (OPLs) and oral squamous cell carcinoma facilitates treatment with less aggressive approaches and results in a better prognosis. The authors conducted a study to identify current practices in the diagnosis and management of these oral lesions by oral medicine professionals.

METHODS

The authors sent a questionnaire to 176 diplomates of the American Board of Oral Medicine and asked them to complete the questionnaires and return them by mail.

RESULTS

The initial clinical approach taken by most of the responders included visual examination, elimination of possible local causes and two-week follow-up. Adjuvant clinical tests included toluidine blue, oral brush biopsy and exfoliative cytology. If there was no clinical improvement after two weeks, most responders recommended that a biopsy be performed. Induration, red component, nonhomogeneous surface and ulceration were characteristics of lesions that increased the responders' decisions to perform a biopsy. Lesion symptoms and location also contributed to their decisions to perform a biopsy. Follow-up more frequently than twice a year was recommended for red lesions, lesions with histologically confirmed dysplasia or both. Most clinicians recommend a biopsy during follow-up of an OPL whenever the lesion changes in appearance.

CONCLUSIONS

The findings of this survey may provide background for initial guidelines to be used by oral practitioners to diagnose and manage OPL. Clinicians' awareness of the complexity of OPL diagnosis and management is important, and referral to an experienced provider is recommended.

Natural history of potentially malignant oral lesions and conditions: an overview of the literature

At a workshop coordinated by the WHO Collaborating Centre for Oral Cancer and Pre-cancer in the UK issues related to potentially malignant disorders of the oral cavity were discussed by an expert group. The consensus views of the Working Group are presented in a series of papers. In this report we review the literature on the epidemiology and natural history of potentially malignant disorders (PMD), detailing those characteristics of the patients and lesions thought to be associated with future development of oral squamous cell carcinoma (OSCC). Older patients, particularly females are more at risk than younger patients; the duration of PMD may be important. Those who have never used tobacco seem at greater risk than smokers. OSCC is more likely with PMD on the lateral and ventral tongue, floor of mouth and retromolar/soft palate complex than with those elsewhere. The vast majority of PMD in which OSCC develop are non-homogenous although 5% of homogenous PMD will develop carcinoma. Large lesions covering several intraoral subsites also appear more at risk.

Nomenclature and classification of potentially malignant disorders of the oral mucosa

At a workshop coordinated by the WHO Collaborating Centre for Oral Cancer and Precancer in the UK issues related to terminology, definitions and classification of oral precancer were discussed by an expert group. The consensus views of the Working Group are presented here. The term, 'potentially malignant disorders', was recommended to refer to precancer as it conveys that not all disorders described under this term may transform into cancer. Critically evaluating all definitions proposed so far for oral leukoplakia, the Working Group agreed that the term leukoplakia should be used to recognize 'white plaques of questionable risk having excluded (other) known diseases or disorders that carry no increased risk for cancer'. An outline was proposed for diagnosing oral leukoplakia that will prevent other oral white disorders being misclassified as leukoplakia. The Working Group discussed the caveats involved in the current use of terminology and classification of oral potentially malignant disorders, deficiencies of these complex systems, and how they have evolved over the past several decades. The terminology presented in this report reflects our best understanding of multi-step carcinogenesis in the oral mucosa, and aspires to engender consistency in use.

Molecular alterations in the tumor suppressor gene WWOX in oral leukoplakias

Oral leukoplakia is the most prevalent and potentially malignant disorder of the oral mucosa. Previous studies have demonstrated that molecular changes of the WWOX gene (WW-domain containing oxidoreductase), a candidate tumor suppressor gene located at 16q23.3-24.1 that spans FRA16D, the second most common fragile site, are present in several malignant neoplasias, including oral squamous cell carcinoma. In this report, the role of the WWOX gene was investigated in 23 cases of oral leukoplakias. Using nested RT-PCR and immunohistochemistry, altered mRNA transcription and/or reduced Wwox protein expression was observed in 35% of the lesions when compared with normal mucosa. The majority of lesions (4/6) with altered transcripts had a reduction in the expression of Wwox protein. Although normal WWOX expression was found in some lesions with dysplasia, all lesions with WWOX mRNA and/or protein expression showed histological evidence of dysplasia and none of the cases without dysplasia presented this alteration. These results show that the WWOX gene alteration is an early genetic alteration and may contribute to oral carcinogenesis.

[Exploration of tumor suppressors p16INK4a and p14ARF in oral leukoplakias]

The inactivation of p16 and p14ARF is considered to be an important step in the carcinogenesis of oropharygeal carcinomas. This consideration is supported by the observation of multiple allelic losses in the coding loci of chromosome 9p21 in squamous cell carcinomas and in dysplastic premalignant lesions. The present study hypothesized that comparable alterations already occur in leukoplakia, which are seen as potential predecessors of oral squamous cell carcinomas and that it is possible to differ leukoplakia with from leukoplakia without further malignant transformation. Furthermore we evaluated, whether such leukoplakia show sequence alterations in the genes p16 and p14ARF, which are capable to cause a limitation in gene function. The results show that the LOH pattern in genes p16 and p14ARF occur as well in leuplakia with malignant transformation as in leukoplakia, that do not show clinical alterations. The rate of allelic loss did not differ significantly. Overall, the incidence of allelic loss was lower in leuplakia compared to succeeding squamous-cell carcinomas (p<0,05). The results further illustrated an increase in LOH patterns in dyplastic leukoplakia, without reaching statistical significance. Significant increases in allelic losses were found in heavy smokers, (p < 0,05). PCR analysis of the exons 1-alpha, exon 1-beta and exon 2 in leukoplakia, containing LOH patterns did not show genetic alterations. Thus we concluded, that gene deletion and gene mutation have a minor role in the inactivation process of p16 and p14ARF in oral leukoplakia. Representing an early process in carcinogenesis, gene deletion and mutation occur in leukoplakia with and without malignant transformation. Therefore, taken as a singular parameter they represent an uncertain criteria to assess the potential of malignant transformation. However they could provide information in combination with other genetic factors like chromosomal methylation patterns and histology.

Nuclear localization of beta-catenin involved in precancerous change in oral leukoplakia

Background

Oral leukoplakia is a precancerous change developed in the oral mucosa, and the mechanism that oral leukoplakia becomes malignant through atypical epithelium is not known. Here we compared the β-catenin expression detected by immunohistochemical staining in the normal oral epithelium and in the oral leukoplakia with or without dysplasia.

Results

The normal oral epithelium showed β-catenin expression only in the cell membrane, but not in the nuclei. In the oral leukoplakia without dysplasia, 7 out of 17 samples (41%) showed β-catenin expression in the cell membrane, and 5 samples (29%) showed expression in the nuclei. In the oral leukoplakia with dysplasia, nuclear expression of β-catenin was shown in 11 out of 12 samples (92%). Incidence of nuclear β-catenin expression was significantly different between dysplasia and normal oral epithelium (P < 0.01), and also between oral leukoplakia with dysplasia and those without dysplasia (P < 0.01). Wnt3 expression was detected in the epithelial cell membrane or cytoplasm in oral leukoplakia where nuclear expression of β-catenin was evident, but not in epithelial cells without nuclear expression of β-catenin.

Conclusion

The components of canonical Wnt pathway, such as Wnt3, β-catenin, and cyclin D1, were detected, implying that this pathway is potentially involved in the progression of dysplasia in oral leukoplakia.

The high-risk benign tumor: evidence from the two-stage skin cancer model and relevance for human cancer

Benign tumors that form following chemical initiation and promotion in the mouse skin can be grouped into two classes. The majority of papillomas do not progress to squamous cell carcinoma (SCC), and these are designated as low-risk or terminally benign papillomas. In contrast, a much smaller group forms the true precursor to the SCC, and these have a significantly higher frequency and rate of malignant conversion than the bulk of low-risk papillomas. In standard two-stage carcinogenesis studies both tumor types are present, but grossly indistinguishable. Here we describe properties and potential origins of high-risk papillomas and discuss the relevance of this model for certain human cancers with defined premalignant states.

Lewis x is highly expressed in normal tissues: a comparative immunohistochemical study and literature revision

An immunohistochemical analysis was employed to determine the expression of carbohydrate antigens associated to mucins in normal epithelia. Tissue samples were obtained as biopsies from normal breast (18), colon (35) and oral cavity mucosa (8). The following carbohydrate epitopes were studied: sialyl-Lewis x, Lewis x, Lewis y, Tn hapten, sialyl-Tn and Thomsen-Friedenreich antigen. Mucins were also studied employing antibodies against MUC1, MUC2, MUC4, MUC5AC, MUC6 and also normal colonic glycolipid. Statistical analysis was performed and Kendall correlations were obtained. Lewis x showed an apical pattern mainly at plasma membrane, although cytoplasmic staining was also found in most samples. TF, Tn and sTn haptens were detected in few specimens, while sLewis x was found in oral mucosa and breast tissue. Also, normal breast expressed MUC1 at a high percentage, whereas MUC4 was observed in a small number of samples. Colon specimens mainly expressed MUC2 and MUC1, while most oral mucosa samples expressed MUC4 and MUC1. A positive correlation between MUC1VNTR and TF epitope (r=0.396) was found in breast samples, while in colon specimens MUC2 and colonic glycolipid versus Lewis x were statistically significantly correlated (r=0.28 and r=0.29, respectively). As a conclusion, a defined carbohydrate epitope expression is not exclusive of normal tissue or a determined localization, and it is possible to assume that different glycoproteins and glycolipids may be carriers of carbohydrate antigens depending on the tissue localization considered.

Factors associated with underdiagnosis from incisional biopsy of oral leukoplakic lesions

OBJECTIVES

Incisional biopsy is accepted by most clinicians as a dependable way of assessing the nature of oral leukoplakia (OL). The aim of the present study was to investigate its reliability and analyze risk factors associated with underdiagnosis from incisional biopsy.

STUDY DESIGN

A cross-sectional retrospective study was conducted in 242 patients with a clinical diagnosis of OL. The discrepancy between provisional diagnosis (from incisional biopsy) and definitive diagnosis (from resection specimen) was analyzed and correlated with clinical variables. Patients who had incisional biopsy taken from a single location and those who received multiple-site biopsies were analyzed separately.

RESULTS

In the 200 cases receiving single-site biopsy, the agreement rate between provisional and definitive diagnoses was only 56%, and underdiagnosis from incisional biopsy was noted in 29.5% of patients. Underdiagnosis rate in the 42 patients receiving multiple-site biopsies was significantly lower (11.9%; P < .05). The rate of unexpected carcinoma in resection specimen was also significantly lower in the multiple-biopsy patients than in the single-biopsy patients (2.4% vs. 12.0%; P < .05). For the single-biopsy group, multivariate analysis revealed that clinical appearance significantly influenced the risk of underdiagnosis and unexpected carcinoma (both P < .05). Compared with homogeneous lesions, nonhomogeneous OL were more prone to be underdiagnosed (adjusted odds ratio [AOR] 2.36, 95% confidence interval [CI] 1.16-4.82) and have carcinoma undetected by incisional specimen (AOR 15.94, 95% CI 2.09-121.72).

CONCLUSIONS

Incisional biopsy was found to have limitations in the assessment of OL, especially for nonhomogeneous lesions. Clinicians should be conscious of the possible underdiagnosis from incisional biopsy, and multiple biopsies should be taken whenever they think that it is necessary.

DNA content, Cyclooxygenase-2 expression and loss of E-cadherin expression do not predict risk of malignant transformation in oral lichen planus

Oral lichen planus (OLP) may be associated with a small risk of malignant transformation of the oral mucosa. Using cases which had transformed, and those which had not, this study aimed to evaluate the potential of DNA content, expression of Cyclooxygenase-2 (Cox-2) and of epithelial (E)-cadherin as risk markers in lesions of OLP. We investigated 78 archival biopsies from; (1) 26 OLP patients with at least two biopsies, of whom seven presented OLP with epithelial dysplasia, followed by oral squamous cell carcinoma (OSCC) in five of them, (2) 19 OLP patients with one biopsy taken. Image cytometry for measurement of DNA content and immunohistochemistry for visualisation of Cox-2 and E-cadherin expression were performed. All OLP biopsies investigated were classified as diploid, one OLP with epithelial dysplasia was tetraploid and all OSCC were diploid. Cox-2 was detected in the epithelium of all OLP specimens investigated, as well as in epithelial dysplasias and OSCC. Focal loss of E-cadherin expression was observed in basal keratinocytes in 88% of the OLP specimens investigated, in all epithelial dysplasias and OSCC. In conclusion, neither aneuploidy, Cox-2 expression, nor loss of E-cadherin expression, were significant reliable markers to select OLP lesions at risk for development of OSCC in the present patient material.

Malignant transformation in 1458 patients with potentially malignant oral mucosal disorders: a follow-up study based in a Taiwanese hospital

BACKGROUND

It is generally accepted that the development of cancer in the oral mucosa is preceded by an identifiable non-invasive precursor lesion. The aim of this follow-up study was to estimate the rate and the time to transformation in a group of patients from southern Taiwan with potentially malignant oral epithelial lesions.

METHODS

The follow-up time is defined as the duration between the onset of the initial diagnosis and the occurrence of confirmed oral cancer. A total of 1458 patients with histological diagnoses of various pre-malignant oral lesions were followed up between 1991 and 2001. The average age at initial diagnosis was 47.5 years. The histological diagnoses were divided into six categories: epithelial dysplasia with hyperkeratosis/epithelial hyperplasia (8.85%); epithelial dysplasia with submucous fibrosis (2.54%); submucous fibrosis (27.57%); hyperkeratosis/epithelial hyperplasia (29.01%); lichen planus (9.80%) and verrucous hyperplasia (22.22%).

RESULTS

Within the cohort of 1458 patients, 44 patients progressed to oral cancer in the same site as the initial lesions with an overall transformation rate of 3.02% and a mean follow-up time of 42.64 months. Eight of the 166 patients with dysplastic lesions and 15 of 423 patients with hyperkeratosis/epithelial hyperplasia progressed to malignancy. The other patients with malignant transformation originated from various pre-cancerous oral lesions and conditions (submucous fibrosis, eight of 402; lichen planus, three of 143; verrucous hyperplasia, 10 of 324).

CONCLUSION

These results indicate that patients with pre-malignant oral lesions need long-term follow up.

Expression of Ki-67 and p53 in cutaneous free flaps used to reconstruct soft tissue defects following resection of oral squamous cell carcinoma

Radial forearm free flaps are used routinely to reconstruct oro-facial tissues following resection of oral squamous cell carcinoma. Surprisingly, there is little information regarding their behaviour following engraftment. The present report is a clinico-pathological study of 10 patients who had incisional biopsies of cutaneous free flaps after the presence of a white patch or erythema raised clinical suspicion. Tissues were stained with haematoxylin and eosin, diastase-periodic acid-Schiff reagent and labelled immunohistochemically for Ki-67 and p53. Four of 10 specimens showed severe epithelial dysplasia within the graft, which was contiguous with dysplasia in the adjacent oral mucosa; the remaining grafts had features typical of candidosis (n=4) or hyperkeratosis (n=2). Grafts with dysplasia had a significantly higher Ki-67 labelling index than lesions in the 'non-dysplastic' group. There were no significant differences in the Ki-67 labelling index between areas of dysplasia in the graft and areas of dysplasia in the adjacent oral epithelium. p53 staining was present in all strata of the epithelium in the dysplastic grafts and adjacent dysplastic mucosa, but was absent or weakly expressed in the stratum basale of grafts showing reactive changes only. None of the dysplastic lesions progressed to carcinoma despite a mean follow-up period of 32 months; one patient developed a recurrent mucosal tumour at the resection margin. These observations indicate that cutaneous free flaps grafted to a site of field cancerisation can develop severe epithelial dysplasia with concomitant deregulation of proliferation and increased p53 expression. Such changes raise the possibility that these lesions have the potential for malignant transformation.

Molecular genetics of premalignant oral lesions

Oral squamous cell carcinoma (OSCC) is characterized by cellular and subcellular alterations that are associated with a progression towards dedifferentiation and growth. There are several histologically distinct lesions of the oral cavity which have malignant potential. These are leukoplakia, erythroplakia, lichen planus, and submucous fibrosis. These are characterized by a spectrum of chromosomal, genetic, and molecular alterations that they share with each other as well as with the malignant lesions that develop from them. In this review we summarize the investigation of the molecular genetics of each of these lesions and relate them to the alterations, which have been demonstrated in OSCC, to define their location on the continuum of changes, which lead to malignant transformation.

Management of oral epithelial dysplasia: a review

One of the goals of the fourth meeting of The World Workshop on Oral Medicine (WWOM IV) included a review of the pathophysiology and future directions for the clinical management of patients with oral epithelial dysplasia, excluding the lips and oropharynx. In the pathophysiology review of dysplasia since WWOM III (1998-2006), a wide range of molecular changes associated with progression of dysplasia to squamous cell carcinoma were found. These include loss of heterozygosity, dysregulation of apoptosis, aberrant DNA expression, and altered expression of numerous tissue markers. Based on the literature search, no single molecular pathway has been identified as the primary factor in progression of dysplasia to squamous cell carcinoma. A systematic review of medical (i.e., nonsurgical) management strategies for the treatment of dysplastic lesions has shown promising results in short-term resolution of dysplasia in the small number of studies that met eligibility criteria for review. However, because of the limited periods of follow-up reported in these studies, it remains unclear as whether resolution of dysplasia would actually be a long-term benefit of these interventions. This question is particularly germane when it is considered in the context of prevention of future development of squamous cell carcinoma. Because of the lack of randomized controlled trials that have shown effectiveness in the prevention of malignant transformation, no recommendations can be provided for specific surgical interventions of dysplastic oral lesions either.

Evaluation of a new binary system of grading oral epithelial dysplasia for prediction of malignant transformation

The aim of this paper is to assess the reproducibility of a novel binary grading system (high/low risk) of oral epithelial dysplasia and to compare it with the WHO classification 2005. The accuracy of the new system for predicting malignant transformation was also assessed. Ninety-six consecutive oral epithelial dysplasia biopsies with known clinical outcomes were retrieved from the Oral Pathology archives. A pilot study was conducted on 28 cases to determine the process of classification. Four observers then reviewed the same set of H&E stained slides of 68 oral dysplastic lesions using the two grading systems blinded to the clinical outcomes. The overall inter-observer unweighted and weighted kappa agreements for the WHO grading system were Ks = 0.22 (95% CI: 0.11-0.35), Kw = 0.63 (95% CI: 0.42-0.78), respectively, versus K = 0.50 (95% CI: 0.35-0.67) for the new binary system. Interestingly, all pathologists showed satisfactory agreement on the distinction of mild dysplasia from severe dysplasia and from carcinoma in situ using the new WHO classification. However, assessment of moderate dysplasia remains problematic. The sensitivity and specificity of the new binary grading system for predicting malignant transformation in oral epithelial dysplasia were 85% and 80%, respectively and the accuracy was 82%. The new binary grading system complemented the WHO Classification 2005 and may have merit in helping clinicians to make critical clinical decisions particularly for the cases of moderate dysplasia. Histological grading of dysplasia using established criteria is a reproducible prognosticator in oral epithelial dysplasia. Furthermore, the present study showed that more consensus scoring on either the degree of dysplasia, assessment of risk or the presence of each morphological characteristic by a panel should be encouraged.

Why oral histopathology suffers inter-observer variability on grading oral epithelial dysplasia: an attempt to understand the sources of variation

The present study attempted to assess the reasons behind the inter-observer variation in grading oral epithelial dysplasia (OED). Three oral pathologists and one general pathologist examined 68 histological slides of OED lesions of variable grade for scoring the presence of each individual characteristic of the architecture and cytology changes that were established by the 2005 WHO classification. The assigned features in each case were correlated with clinical outcomes to understand which features are more commonly associated with malignant transformation. Interestingly, for all individual characteristics, the pairwise inter-examiner and group kappa values ranged from poor to moderate. It appeared that for each characteristic separately there was much dissension. Despite these observations, comparing these data with that from our previous paper on the same slides showed that the inter-observer agreement on the degree of dysplasia either by using the new binary system of "low-risk" or "high-risk" or by using the 2005 WHO classification turned out to be better than the agreement on the individual characteristics of architecture and cytology changes. Certain features show significant association with the clinical outcomes. In the discussion, some explanations to help understanding the sources of variation in grading OED are put forward. In conclusion, grading dysplasia is not an exact science and pathologists are doing their best to reach optimal results. Improvement in the standard of the histopathology reporting of OED lesions could be achieved by consideration of several issues. Of these, there is need for a universal definition of the architectural and cytological features that are the basis of any OED grading process. A minimum dataset for reporting OED lesions should be set up. Also, the use of a consensus scoring process between two or more observers should be encouraged as this would improve inter-observer agreement.

Differential expression of basement membrane collagen-IV α1 to α6 chains during oral carcinogenesis

This study aimed to resolve if basement membrane (BM) collagen alpha chains undergo remodeling during oral carcinogenesis. Using immunohistochemistry and transmission electron microscopy, we found that BMs in oral epithelial dysplasias (OED: mild, n=10; moderate, n=10; severe, n=10) and carcinoma in situ (CIS) (n=10) differed from normal mucosa (n=6) and oral epithelial hyperplasia (n=5) in showing: (1) excessive lamina densa-like material ultrastructurally, and (2) stronger immunoexpression for alpha5(IV) than for alpha1(IV), alpha2(IV), and alpha6(IV) chains-findings that implicate these molecules' role as an adhesive template for the attachment and persistence of basal dysplastic cells. Incipient loss of BM integrity in CIS, where alpha5(IV)/alpha6(IV) chains were more frequently absent than alpha1(IV)/alpha2(IV) chains, suggests that alpha(IV) network disruption is crucial for progression of dysplastic cells into the extracellular compartment, marking transition into the invasive phase. In carcinomatous BM, the disappearance of alpha(IV) chains was more severe in poorly differentiated oral squamous cell carcinoma (OSCC) (n=10) than in well-differentiated OSCC (n=10). In all samples examined, alpha3(IV) and alpha4(IV) chains were absent. These findings taken together suggest that BM collagen-IV alpha chains undergo remodeling where selective increase and loss of these molecules are probably early and late events, respectively, during progression of oral dysplasia to cancer.

Oxidative and nitrative DNA damage in animals and patients with inflammatory diseases in relation to inflammation-related carcinogenesis

Infection and chronic inflammation are proposed to contribute to carcinogenesis through inflammation-related mechanisms. Infection with hepatitis C virus, Helicobacter pylori and the liver fluke, Opisthorchis viverrini (OV), are important risk factors for hepatocellular carcinoma (HCC), gastric cancer and cholangiocarcinoma, respectively. Inflammatory bowel diseases (IBDs) and oral diseases, such as oral lichen planus (OLP) and leukoplakia, are associated with colon carcinogenesis and oral squamous cell carcinoma (OSCC), respectively. We performed a double immunofluorescence labeling study and found that nitrative and oxidative DNA lesion products, 8-nitroguanine and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), were formed and inducible nitric oxide synthase (iNOS) was expressed in epithelial cells and inflammatory cells at the site of carcinogenesis in humans and animal models. Antibacterial, antiviral and antiparasitic drugs dramatically diminished the formation of these DNA lesion markers and iNOS expression. These results suggest that oxidative and nitrative DNA damage occurs at the sites of carcinogenesis, regardless of etiology. Therefore, it is considered that excessive amounts of reactive nitrogen species produced via iNOS during chronic inflammation may play a key role in carcinogenesis by causing DNA damage. On the basis of our results, we propose that 8-nitroguanine is a promising biomarker to evaluate the potential risk of inflammation-mediated carcinogenesis.

Long-term treatment outcome of oral premalignant lesions

The purpose of the present retrospective study was to learn the long-term outcome of oral premalignant lesions, leukoplakia and erythroplakia, with or without surgical intervention and to relate the outcome to factors supposed to be significant for malignant development including clinical type, demarcation, size, site, presence of epithelial dysplasia, smoking and surgery. A total of 269 lesions in 236 patients were included. Ninety-four lesions were surgically removed, 39 lesions (41%) being homogenous and 46 (49%) non-homogenous leukoplakias whereas nine (5%) were erythroplakias. Seventy-three percent of the lesions were associated with tobacco habits. The mean size of the lesions was 486 mm(2), and 71% of the lesions showed a degree of epithelial dysplasia. After excision the defects were closed primarily by transposition of mucosal flaps or they were covered by free mucosal or skin grafts. A few defects were left for secondary healing. After surgical treatment the patients were followed (mean 6.8 yrs, range 1.5-18.6 yrs), and new biopsies taken in case of recurrences. One hundred and seventy five lesions had no surgical intervention, 149 lesions (85%) being homogenous and 20 (11%) non-homogenous leukoplakias, and 6 (3%) erythroplakias. Eighty-one percent of the lesions were associated with smoking. The mean size of the lesions was 503 mm(2) and 21 of the lesions (12%) exhibited epithelial dysplasia. Sixty-five lesions were not biopsied. These patients were also followed (mean 5.5 yrs, range 1.1-20.2 yrs), and biopsies taken in case of changes indicative of malignant development. All patients were encouraged to quit smoking and candidal infections were treated. The possible role of different variables for malignant development was estimated by means of logistic regression analysis. Following surgical treatment 11 lesions (12%) developed carcinoma after a mean follow-up period of 7.5 yrs. Non-homogenous leukoplakia accounted for the highest frequency of malignant development, i.e. 20%, whereas 3% of the homogenous leukoplakias developed carcinomas. Surgically treated lesions with slight, moderate, severe and no epithelial dysplasia developed carcinoma with similar frequencies, i.e. 9-11%. Without surgical intervention 16% of the 175 lesions disappeared whereas seven lesions (4%) developed carcinoma after a mean observation period of 6.6 yrs. The highest frequency of malignant development (15%) was seen for non-homogenous leukoplakias, this figure being 3% for homogenous leukoplakias. Fourteen percent of lesions with slight epithelial dysplasia developed malignancy and 2% of lesions with no dysplasia showed malignant transformation. Logistic regression analysis showed a seven times increased risk (OR = 7.0) of non-homogenous leukoplakia for malignant development as compared with homogenous leukoplakia and a 5.4 times increased risk for malignant development for lesions with a size exceeding 200 mm(2). No other examined variables including presence of any degree of epithelial dysplasia, site, demarcation, smoking and surgical intervention were statistically significant factors for malignant development.

Disease mechanism and biomarkers of oral squamous cell carcinoma

PURPOSE OF REVIEW

This review focuses on oral cancer disease mechanisms and discusses ongoing research to identify molecular signatures or biomarkers for oral cancer. Other areas covered include the analysis, validation, and predictive value of these markers.

RECENT FINDINGS

During the past years, progress has been made in the oral cancer genetic markers field, which includes alterations of the p53 tumor suppressor protein, the inactivation of cyclin dependant kinase inhibitors (e.g. p16) and the overexpression of the epidermal growth factor receptor. Many of these markers are thought to have potential clinical interest, yet few of them are being used in a clinical setting for oral cancer management. The particular modifications that characterize each step of oral cancer progression can now be profiled by several high throughput discovery techniques. Genomic and proteomic studies of oral cancer tissues, plasma, and saliva of oral cancer patients, have allowed the identification of several promising cancer signatures.

SUMMARY

Important progress has been made in the molecular understanding of oral cancer and its application for diagnosis, prognosis and treatment. The increased efforts in translational research will result in earlier diagnosis of oral cancer, better knowledge of prognostic factors, and the development of targeted treatment regimens based on patients' clinical and biological characteristics at presentation.

Oral premalignancy: new methods of detection and treatment

Oral carcinogenesis proceeds through a stepwise accumulation of genetic damage over time. Because the oral cavity is easy to examine and risk factors for oral cancer are known, there is great opportunity to improve patient outcomes through diagnosis and treatment of pre-malignant lesions before the development of invasive oral carcinoma. This review provides a summary of developments in detection and diagnosis of oral premalignant lesions and innovative approaches to management of early oral neoplasia. These technological and therapeutic advances are much needed to improve the poor outcomes associated with oral cancer due to our inability to diagnose and treat this disease at an early, curable stage.

8-Nitroguanine formation in oral leukoplakia, a premalignant lesion

Oral leukoplakia is a premalignant lesion associated with development of oral cancer. To clarify the mechanism of development of oral carcinogenesis from leukoplakia, we examined DNA damage in oral epithelium of biopsy specimens of patients with leukoplakia by immunohistochemical methods. Histological changes, such as epithelial dysplasia and infiltration of inflammatory cells were observed in oral tissues of leukoplakia patients. A double immunofluorescence labeling study demonstrated that the accumulation of mutagenic 8-nitroguanine, an indicator of nitrative DNA damage, and 8-oxo-7,8-dihydro-2'-deoxyguanosine, an indicator of oxidative DNA damage, was apparently observed in the oral epithelium of patients with leukoplakia, whereas little or no immunoreactivity was observed in normal oral mucosa. Expression of inducible nitric oxide synthase (iNOS) was also observed in oral epithelium of leukoplakia patients. Immunoreactivity of 3-nitrotyrosine, an indicator of nitrative stress, was observed in oral epithelial cells and colocalized with 8-nitroguanine. Moreover, proliferating cell nuclear antigen and p53 were expressed in 8-nitroguanine-positive epithelial cells in the basal layer. These results suggest that iNOS-mediated nitrative stress contributes to development of oral carcinogenesis from leukoplakia through DNA damage as well as oxidative stress.

H3 and H3.3 histone mRNA amounts and ratio in oral squamous cell carcinoma and leukoplakia

Histone variants (e.g. H3) play an important role in chromatin structure and gene expression regulation of normal cells. Aims of this study were to: (1) estimate H3 and H3.3 histone mRNA expressions and their ratio in oral squamous cell carcinoma (OSCC) and oral leukoplakia (OL); (2) investigate whether H3 and H3.3 variants could play a role in the pathogenesis of OSCC and OL, also conditionally to HPV infection, age, gender, and main habits (tobacco smoking and alcohol drinking) in human beings studied. Twenty-three cases of OSCC and 20 cases of OL were examined in lesion site (LS) and juxtaposed clinically undamaged site (JUS) by RT-PCR for H3 and H3.3 histone mRNA; 13 healthy oral mucosa samples (HS) were investigated in a single site as controls. HPV DNA presence was investigated in the respective exfoliated oral mucosa cells by nested PCR (nPCR: MY09-MY11/GP5-GP6). The data showed that both H3 and H3.3 histone mRNA crude concentrations are higher in OSCC (LS = 2901 +/- 459 ng of H3; JUS = 2699 +/- 658 ng of H3; LS = 3190 +/- 411 ng of H3.3; JUS = 2596 +/- 755 ng of H3.3) than those in OL (LS = 2095 +/- 349 ng of H3; JUS = 2192 +/- 897 ng of H3; LS = 2076 +/- 911 ng of H3.3; JUS = 1880 +/- 654 ng of H3.3) and in HS (2579 +/- 959 ng of H3; 2300 +/- 758 ng of H3.3), although not reaching any statistical significance. Interestingly, ratio of H3/H3.3 mRNA amounts decrease both in OSCC (0.99) and OL (1.009) vs HS (1.121). No association was found for H3 and H3.3 histone mRNA expressions in OSCC and OL with respect to HPV infection and the social-demographical variables considered (P > 0.2). The overall higher expression of H3.3 in damaged tissues up to the ratio inversion in OSCC especially in HPV+ alcohol drinkers (60.0%) represents the most interesting finding, in consideration of the proven ability of alcohol to act as permeability enhancer of human oral mucosa, to alter the mucosal structure and by this dynamics could favour the penetration through the epithelial layers of HPV.