Oral leukoplakia, with emphasis on malignant transformation. A follow-up study of 46 patients

Treatment outcomes of oral leukoplakia on the irradiated or nonirradiated mucosa among survivors of head and neck cancer in the papulation where practice of betel nut chewing and cigarette smoking are widespread

BACKGROUND

Radiotherapy (RT) has numerous effects on the oral mucosa, primarily genetic alterations and changes in the microenvironment. The characteristics of oral leukoplakia (OL) may differ between patients who have received previous head and neck cancer (HNC) treatment with radiation therapy and those who have not. Due to a lack of data on this scenario, we aimed to investigate the surgical outcomes of OL by comparing these two patient groups.

METHODS

This retrospective cohort study enrolled a total of 224 OL lesions in 124 patients who underwent carbon dioxide laser (CO2 laser) surgery from July 2002 to Aug 2021. All patients had received previous treatments for HNC, with 59 patients undergoing only surgical approach, 65 patients undergoing RT, and 46 patients undergoing concurrent chemotherapy during RT. The analysis was performed on a per-lesion basis, not a per-capita basis. We investigated the associations of clinicopathological characteristics and treatment outcomes of OL lesions that developed from irradiated or nonirradiated oral mucosa.

RESULTS

The median follow-up time was 5.87 years. Postoperative recurrence of OL occurred in 30 patients. Malignant transformation occurred in 17 patients with the incidence rate 4.19% annually and 13.7% cumulatively. The average time for OL transforming into squamous cell carcinoma was 3.27 ± 3.26 years (median 1.82, range 0.11 - 11.90). In univariate analysis, non-homogeneous morphology (P = 0.042), moderate to high-grade dysplasia (P = 0.041), and nonirradiated oral mucosa (P = 0.0047) were predictors for malignant transformation. However, in the Cox proportional hazard model, only nonirradiated oral mucosa remained an independent prognostic factor related to postoperative malignant transformation of OL (P = 0.031, HR 5.08, CI95 1.16 - 22.25).

CONCLUSION

In the population whose OL is strongly aetiologically linked to environmental carcinogens such as betel nut and tobacco, OL lesions that develop on previously irradiated oral mucosa have a lower risk for postoperative malignant transformation compared to those that develop on nonirradiated mucosa. This finding highlights the potential impacts of radiation on OL. Further research is needed to confirm this observation and elucidate the underlying mechanism.

Clinical outcomes of oral epithelial dysplasia managed by observation versus excision

IMPORTANCE

Oral potentially malignant disorders, including oral epithelial dysplasia (OED), are a group of conditions with an increased risk of progression to oral cancer. Clinical management of OED is challenging and usually involves monitoring with repeated incisional biopsies or complete surgical excision.

OBJECTIVE

To determine if complete surgical excision of OED impacts malignant transformation or improves survival outcomes in lesions that progress to malignancy.

DESIGN

A retrospective review of all patients diagnosed with OED between 2009 and 2016 was completed, and patients were followed until January 2022 for disease course and outcomes.

RESULTS

Hundred and fifty-five cases of OED met the inclusion criteria. Among the 61 lesions managed by observation, 15 progressed to cancer. Among the 94 lesions managed by surgical excision, 27 progressed to cancer. The overall malignant transformation rate was 27%, with an annual rate of 6.4%. Surgical excision with or without histologically negative margins did not decrease malignant transformation but was associated with lower oncologic staging at the time of diagnosis and improved survival.

CONCLUSIONS AND RELEVANCE

Surgical excision of OED with or without negative margins did not reduce the rate of transformation to oral cancer but resulted in lower oncologic staging at diagnosis, leading to improved patient outcomes. Our results support the implementation of more extensive tissue sampling to improve cancer diagnosis and patient outcomes.

Azoxystrobin induces apoptosis via PI3K/AKT and MAPK signal pathways in oral leukoplakia progression

Background: Oral leukoplakia (OLK) is one of the oral potentially malignant disorders (OPMDs) with an increased risk of developing oral squamous cell carcinoma (OSCC). There is no ideal therapeutic drug yet. Our previous study showed azoxystrobin (AZOX) inhibited the viability of OLK cells and the incidence of mouse tongue cancer. However, its specific mechanism has not been clarified. Here, we used network pharmacology with experimental validation to investigate the roles and mechanisms of AZOX in OLK.

Methods: The targets of AZOX and OLK were obtained from online databases. The overlapping genes were identified by the Jvenn database. STRING and Cytoscape software were used to construct the PPI network. GO and KEGG enrichment analyses were used to analyze the biological function. Molecular docking and CETSA were used to verify the direct binding between AZOX and its key targets. 4NQO induced mouse tongue carcinogenesis model was constructed to clarify the treatment response of AZOX in vivo. TUNEL staining was performed to detect the effect of AZOX on apoptosis in mouse OLK tissues. CCK8 assay, flow cytometry, and western blot were used to detect the effect of AZOX on cell proliferation and apoptosis in DOK cells. The expression of PI3K/AKT and MAPK markers were analyzed by immunohistochemistry in vivo or by western blot in vitro.

Results: Venn diagram showed 457 overlapping targets, which were involved in the PI3K/AKT, MAPK, and apoptosis pathways, and the top 5 hub modules were TP53, STAT3, AKT1, MAPK1, and PIK3R1. AZOX was bound with the highest force to AKT and PI3K by AutoDock Vina. PyMOL software visualized that AZOX could fit in the binding pocket of the AKT and PI3K. The carcinogenesis rate of the mouse OLK in the high-dose AZOX group was significantly reduced. AZOX induced apoptosis in the OLK tissues and DOK cells, and the expression of PI3K, AKT, p-ERK was decreased, and the expression of p-p38 and p-JNK was increased. CETSA indicated that AZOX might have a direct binding with AKT and PI3K.

Conclusion: AZOX may induce apoptosis via PI3K/AKT and MAPK pathways in OLK. This study reveals the potential therapeutic targets of AZOX in OLK.

A Retrospective Cohort Study of Oral Leukoplakia in Female Patients-Analysis of Risk Factors Related to Treatment Outcomes

Background: The aim of this study was to make a comparison of clinicopathological characteristics of oral leukoplakia between male and female patients following carbon dioxide laser excision for oral leukoplakia and analyze the factors associated with the treatment outcomes in female patients. Methods: Medical records of patients with oral leukoplakia receiving laser surgery from 2002 to 2020 were retrospectively reviewed and analyzed statistically. Results: A total of 485 patients were enrolled, including 412 male (84.95%) and 73 female (15.05%). Regarding the locations, the predilection site of oral leukoplakia in male patients was buccal mucosa (p = 0.0001) and that for women patients was tongue (p = 0.033). The differences of recurrence and malignant transformation between both sexes were not significant (p > 0.05). Among female patients, area of oral leukoplakia was the risk factor related to recurrence (p < 0.05). Clinical morphology and postoperative recurrence were the risk factors related to malignant transformation (p < 0.05). Conclusions: In comparison with male patients, there was no significant difference of the postoperative recurrence and malignant transformation of oral leukoplakia in female patients. Among the female patients, clinicians should pay more attention to large-sized and non-homogeneous leukoplakia, and postoperative recurrent lesions.

Difficulties in the Prognostic Study of Oral Leukoplakia: Standardisation Proposal of Follow-Up Parameters

Oral leukoplakia is the most prevalent potentially malignant disorder of the oral cavity. To evaluate its potential for malignancy, appropriate documentation of the biological parameters is crucial, allowing the patients' progression to be assessed. We hypothesized a lack of standardization in the parameters employed for the prognostic study of oral leukoplakia; our aims were to determine the different parameters used for follow-up according to definition, importance, and frequency of use, and to provide a standardization proposal of follow-up research. We made a scoping review to identify papers with the keywords “leukoplakia,” “oral,” and “follow-up” published until June 2019 in English, Spanish and Portuguese literature through an online search in PUBMED, SCIELO, and SCOPUS databases. In total, 514 articles were initially identified, and fifty-nine publications were selected, of which 37 were retrospective. The reports included a total of 18,660 patients between 13 and 98 years old, with a mean age of 57.6 years. Tobacco and alcohol habits were positive for 77 and 37% of the patients, respectively. Our results showed that reported leukoplakias were predominantly located on buccal mucosa (40.4%), were homogeneous (60.8%), multiple (59.9%), smaller than 2 cm (74.4%) and histopathologically non-dysplastic (71%). The mean follow-up time was 55 months, with a 13% malignant transformation rate. The categorization and definition of multiple variables were notably diverse. Age, sex, habits (tobacco and alcohol), site, size, distribution, morphology, degree of dysplasia, and evolution were the chosen parameters for our proposal. The current study reflected the lack of consensus found in the literature regarding parameters for diagnosis or follow-up, impacting negatively on clinical and research results. standardization comprises an efficient way to facilitate the prognosis assessment of oral leukoplakia, being beneficial for clinical practice, and enabling better quality information to apply in research.

Annual malignant transformation rate of oral leukoplakia remains consistent: A long-term follow-up study

OBJECTIVES

Numerous clinical and histopathological characteristics have been associated with malignant transformation (MT) of oral leukoplakia (OL), including classic and differentiated epithelial dysplasia, but MT predictions remain suboptimal. The objective of this study was to determine the annual MT rate of OL and to identify clinicopathological risk factors associated with MT.

PATIENTS AND METHODS

170 patients with OL were included in this retrospective cohort study, 117 females and 53 males. Follow-up ranged from 12 to 219 months (median 54). The analyzed variables included age, gender, smoking habits, clinical presentation, subsite, size and treatment. In a subgroup of 140 patients, histopathological diagnoses were reviewed with regard to the presence of dysplasia, discerning both classic dysplasia and differentiated dysplasia.

RESULTS

MT occurred in 23% of the patients, resulting in an annual MT rate of 4.9% (95% CI: 3.5 - 6.6) which remained consistent. High-risk subsite (tongue and floor of mouth) was the only clinical predictor for MT (Hazard Ratio = 2.7, 95% CI: 1.3 - 5.5, p = 0.007). In 140 patients, classic dysplasia (Hazard Ratio = 7.2, 95% CI: 1.6 - 33.1, p = 0.012) and differentiated dysplasia (Hazard Ratio = 6.6, 95% CI: 1.2 - 25.4, p = 0.026) were predictors for MT. Binary grading between dysplasia and no dysplasia was significant for predicting MT (Hazard Ratio = 6.4, 95% CI: 1.5 - 27.5, p = 0.013).

CONCLUSION

Since annual MT rate of OL remains stable during follow-up, regular long-term or even life-long follow-up is advocated. Specific oral subsites and epithelial dysplasia are predictors for MT of OL.

Malignant transformation rate of oral leukoplakia-systematic review

OBJECTIVE

The aim of this study was to perform a systematic review of prevalence studies to determine the rate of malignant transformation of oral leukoplakia and assess the influence of demographic factors (age, gender, and geographic region) on the overall transformation rate.

STUDY DESIGN

A search was conducted for publications until July 2019 in 4 electronic databases and peer-reviewed journals. A manual search was performed on the bibliographies of the collected articles, and the authors were contacted for additional information. This study was previously registered with the trial number CRD42019126909 and study quality assessed through established methods. The results were expressed by means of proportions or odds ratios with a 95% confidence interval. Meta-regression was undertaken to evaluate possible sources of heterogeneity, and funnel plot visual analysis was performed to assess publication bias.

RESULTS

The 34 observational epidemiologic studies included reported data on 26,209 patients with oral leukoplakia from 18 different countries. Meta-analysis of 32 studies (23,489 patients) presented an estimated overall mean proportion of malignant transformation rate of 9.70% (7.80-11.70) (I² = 98.66%; τ² < 0.001; χ² = 23.18; degrees of freedom [df] = 31). When comparing genders, the odds ratio favored males with 0.622 (0.468-0.826) (I² = 29.77%; τ² = 0.089; χ² = 22.78; df = 16).

CONCLUSIONS

Within the limitations of the included studies in this systematic review, the results suggest that the malignant transformation rate was dependent on demographic factors and follow-up time. Future studies should include the development of guidelines to standardize the methodology for long-term follow-up assessment, thus reducing the risk of bias.

Potentially malignant disorders of the oral cavity and oral dysplasia: A systematic review and meta-analysis of malignant transformation rate by subtype

IMPORTANCE

Potentially malignant disorders of the oral cavity (OPMD) are a heterogeneous group of lesions associated with a variable risk of malignant transformation (MT) to invasive cancer. Leukoplakia (LE), lichen planus (LP), oral lichenoid lesions (OLL), oral erythroplakia (OE), oral submucous fibrosis (OSF), and proliferative verrucous leukoplakia (PVL) are among the most common of these lesions. Oral dysplasia is a mucosal area characterized by cellular and architectural derangement, which may be associated with OPMDs or not.

OBJECTIVE

To define the MT rate of OPMDs and the risk of development into cancer of mild vs moderate/severe oral dysplasia. This in order to implement adequate follow-up strategies and treatment decisions.

STUDY DESIGN

We performed a systematic review and meta-analysis on studies reporting the MT rates of OPMDs and oral dysplasia. Ninety-two studies were included for the analysis. Cumulative rates were reported for OPMDs overall and as a subgroup, a comparison was made of mild vs moderate/severe dysplasia. Meta-regression on OPMD and year of publication was also performed.

MAIN OUTCOME AND MEASURES

Overall MT rates of OPMDs and odds ratio of MT of mild vs moderate/severe dysplasia.

RESULTS

Overall MT rate across all OPMD groups was 7.9% (99% confidence interval [CI] 4.9%-11.5%). MT rates of the specific OPMD subgroups were as follows: LP 1.4% (99% CI 0.9%-1.9%), LE 9.5 (5.9%-14.00%), OLL 3.8% (99% CI 1.6%-7.00%), OSF 5.2% (99% CI 2.9%-8.00%), OE 33.1% (99% CI 13.6%-56.1%), and PVL 49.5% (99% CI 26.7%-72.4%). Regarding the dysplasia grades comparison, the meta-analysis showed that moderate/severe dysplasia is meaningfully associated to a much greater risk of MT compared to mild dysplasia with an odds ratio of 2.4 (95% CI 1.5-3.8) [Correction added on 27 December 2019, after first online publication: CI updated from 99% to 95%.]. Heterogeneity was not significant. Annual MT rates were approximated based on the average follow-up as reported in the various subgroups. Lichen planus had an annual MT of 0.28%, OLL of 0.57%, leukoplakia of 1.56%, PVL of 9.3%, and OSF of 0.98%. Mild dysplasia had an annual MT of 1.7%, while severe dysplasia of 3.57%. Meta-regression showed a significant negative correlation of PVL MT rate and year of the study (P value <.001).

CONCLUSIONS AND RELEVANCE

OPMDs and oral dysplasia are relatively common conditions that general practitioners, head and neck, and oral medicine specialists, face in their everyday practice. Our analysis confirms the significant risk of MT of these lesions, although variable among the subgroups. Moderate/severe dysplasia bears a much higher risk of cancer evolution than mild dysplasia. It is important to raise public health awareness on the MT rates of these conditions, at the same time efficacious communication with the patient is of utmost importance. This, coupled with strict follow-up measures and optimal treatment strategies, would help in reducing the transformation of these oral conditions into invasive cancer.

Quality of life in patients with oral leukoplakia

BACKGROUND

Oral leukoplakia (OL) is the most common oral potentially malignant disorder, yet despite its chronic and potentially disabling nature, the literature concerning impacts of OL on quality of life (QoL) is limited. This study aimed to evaluate QoL in subjects with OL compared to controls using QoL questionnaires.

METHODS

Fifty individuals with OL and 50 controls matched for age, gender, smoking, and alcohol use were administered the Short Generic Health Questionnaire (SF-12) and the discipline-specific Oral Potentially Malignant Disorder Questionnaire (OPMDQ). Responses were compared between the two groups.

RESULTS

Subjects with OL reported poorer QoL scores compared to controls in two domains "Role limitations due to physical problems" and "Pain" of the SF-12 questionnaire, and in two domains "Difficulty with diagnosis" and "Effect of treatment on daily life" and in the overall scores of the OPMDQ. Females reported poorer QoL in the overall OPMD QoL score and in the domains of "Physical and function limitation" and "Psychological and social well-being," while older individuals in the domains of "Physical and function limitation" and "Effect of treatment on daily life." Non-alcohol drinkers and subjects with dysplastic or non-homogeneous OLs also reported poorer QoL scores.

CONCLUSIONS

Quality of life assessments provide useful insight into the impact of OL on an individual's life and opportunity to improve clinical care.

Oral potentially malignant disorders: risk of progression to malignancy

Oral potentially malignant disorders (OPMDs) have a statistically increased risk of progressing to cancer, but the risk varies according to a range of patient- or lesion-related factors. It is difficult to predict the risk of progression in any individual patient, and the clinician must make a judgment based on assessment of each case. The most commonly encountered OPMD is leukoplakia, but others, including lichen planus, oral submucous fibrosis, and erythroplakia, may also be seen. Factors associated with an increased risk of malignant transformation include sex; site and type of lesion; habits, such as smoking and alcohol consumption; and the presence of epithelial dysplasia on histologic examination. In this review, we attempt to identify important risk factors and present a simple algorithm that can be used as a guide for risk assessment at each stage of the clinical evaluation of a patient.

Image-based DNA ploidy analysis aids prediction of malignant transformation in oral lichen planus

OBJECTIVES

To investigate the potential of image-based DNA ploidy analysis to predict malignant transformation in patients with oral lichen planus (OLP).

STUDY DESIGN

DNA ploidy analysis was performed on biopsy samples from 14 patients with OLP who underwent malignant transformation. As controls, 42 OLP lesions showing unusual clinical features suggesting a transformation risk and 68 samples of clinically and histologically typical OLP were included. Cases with dysplasia on initial biopsy were excluded. Eighty fibroepithelial polyps acted as methodologic controls. Epithelial nuclei were isolated from formalin-fixed paraffin embedded biopsy samples and monolayers stained with Feulgen for automated image cytometry to establish DNA content. Ploidy status was correlated to outcome using Kaplan-Meier analysis and log-rank Mantel-Cox tests.

RESULTS

All controls and typical OLP were diploid and none underwent malignant transformation in mean follow-up of 14 years (10-18 years). One unusual OLP developed carcinoma and all were diploid. The 14 patients with transformation developed 21 carcinomas. In the 11 patients who had a prior biopsy, 4 were aneuploid.

CONCLUSIONS

DNA ploidy analysis predicted malignant transformation in more than one third (36.4%) of patients with OLP with a preceding biopsy (n = 11). This premalignant nature could not have been diagnosed clinically or by histologic dysplasia assessment.

Meta-analysis on clinicopathologic risk factors of leukoplakias undergoing malignant transformation

Context:

Leukoplakia is classified under the term potentially malignant disorder. This term does not suggest the clinician or the patient about the severity of the disease to undergo a malignant transformation. Thus, there arises a need to identify the risk factors associated with malignant transformation (MT) to predict it at the earliest.

Aims:

To generate evidence regarding the clinicopathologic factors affecting MT in oral leukoplakias.

Materials and Methods:

Meta-analysis was done by extracting data from all the previous studies published. Articles were searched in PubMed databases.

Statistical Analysis:

Mixed model by using the PROC MIXED (SAS 9.3) was performed to estimate the effect of different factors such as gender, type of habit (smoking tobacco, gutka, paan (with tobacco) and no habit association), clinical type and histopathology on MT. The lower specific mean for MT was also calculated with respect to the above-mentioned factors.

Results:

Speckled leukoplakias also known as erythroleukoplakia confirmed to be at the highest risk. Lateral border of the tongue followed by gingiva, buccal mucosa, floor of the mouth, lesions involving tongue and floor of mouth showed increased risk. Smoking tobacco (cigarette and bidi) and idiopathic leukoplakia (without habit) carried almost equal risk. Gender had minimal influence on MT. Histopathologic correlation of grades showed an insignificant bearing on MT.

Conclusion:

The carcinogenic transformation of a preexisting lesion (leukoplakia) is multifactorial and patient specific. The protocol to delineate a high-risk lesion should include the clinical type and site.

Malignant transformation of oral leukoplakia: a systematic review of observational studies

The aim of this systematic review was to ascertain the malignant transformation rate of oral leukoplakia and the associated risk factors.

METHOD

Published literature was searched through several search engines from 1960 to the end of December 2013. The inclusion criteria included 'leukoplakia', 'pre-cancer', 'malignant transformation', 'follow-up' and 'outcome'. Two reviewers extracted the data independently and also assessed the quality of evidence.

RESULTS

The search strategy resulted in 1032 abstracts or full-text articles, of which 24 met the inclusion criteria. There was much variation in the definitions used by the various authors in their original reports to define oral leukoplakia or in the criteria used to recruit their patients for follow-up. The estimated overall (mean) malignant transformation rate for the total population described in these 24 studies amounts to 3.5% (405/11423), with a wide range between 0.13% and 34.0%. Based on the evidence presented, the features that stand out as significant determinants contributing to malignant potential of OL include advanced age, female sex, leukoplakia exceeding 200 mm(2) , non-homogeneous type (eg. erythroleukoplakia) and the higher grades of dysplasia.

CONCLUSION

The review indicates that drawing meaningful evidence-based conclusions are difficult from retrospective studies of this nature. However, many of the determinants exposed in the review require further investigation by well-designed prospective studies.

Clinical outcome following oral potentially malignant disorder treatment: a 100 patient cohort study

Oral potentially malignant disorders (PMDs) are at risk of transforming to invasive squamous cell carcinoma (SCC), but controversy exists over their management and the precise role of interventional treatment. In this study, a cohort of 100 patients presenting with new, single oral dysplastic PMD lesions were followed for up to 10 years following laser excision. PMDs presented primarily as homogeneous leukoplakias on floor of mouth and ventrolateral tongue sites and showed mainly high-grade dysplasia following analysis of excision specimens. Sixty-two patients were disease-free at the time of the most recent followup, whilst 17 experienced same site PMD recurrence, 14 developed further PMDs at new sites, 5 underwent same site malignant transformation, and 2 developed SCC at new oral sites. Whilst laser excision is an effective therapeutic tool in PMD management, prolonged patient followup and active mucosal surveillance together with clear definitions of clinical outcomes are all essential prerequisites for successful interventional management. Multicentre, prospective, and randomised trials of PMD treatment intervention are urgently required to determine optimal management strategies.

Excision of Oral Leukoplakia by CO2 Lasers Versus Traditional Scalpel: A Comparative Study

PURPOSE

Laser surgery has shown to exhibit several advantages over scalpel for many procedures. Some of these advantages include hemostasis, decreased scarring, and ability to perform certain procedures without anaesthesia. It has been postulated that laser surgery results in less post-operative pain. However this can be a difficult parameter to measure. This study sought to determine if there was a difference in the intensity and frequency of pain following excision with scalpel when compared to excision done with a CO2 laser.

AIMS AND OBJECTIVE

(1) Hemostasis intra operatively and (2) pain, swelling and scarring post-operatively.

MATERIALS AND METHODS

Thirty patients with bilateral (60 lesions) were selected for the entire proposed research. Group A: carbon dioxide laser excision (experimental group). Group B: scalpel excision (control group).

RESULT

(1) Intra operative bleeding is significantly higher in scalpel side compared to laser side treatment. (2) Percentage change (gained) in facial edema is significantly higher in scalpel side compared to laser side treatment. (3) Distribution of level of pain is approximately similar in both the treatments. (4) Distribution of scarring after 1 month post-operative pain is significantly higher in scalpel side compared to laser side treatment.

CONCLUSION

Through this study we can infer that CO2 laser supersedes conventional scalpel in terms of better intra-operative and reduced scarring. Post-operative pain and swelling after laser excision did not show any significant difference from that of scalpel.

Loss of heterozygosity (LOH) profiles--validated risk predictors for progression to oral cancer

A major barrier to oral cancer prevention has been the lack of validated risk predictors for oral premalignant lesions (OPL). In 2000, we proposed a loss of heterozygosity (LOH) risk model in a retrospective study. This paper validated the previously reported LOH profiles as risk predictors and developed refined models via the largest longitudinal study to date of low-grade OPLs from a population-based patient group. Analysis involved a prospective cohort of 296 patients with primary mild/moderate oral dysplasia enrolled in the Oral Cancer Prediction Longitudinal Study. LOH status was determined in these OPLs. Patients were classified into high-risk or low-risk profiles to validate the 2000 model. Risk models were refined using recursive partitioning and Cox regression analyses. The prospective cohort validated that the high-risk lesions (3p and/or 9p LOH) had a 22.6-fold increase in risk (P = 0.002) compared with low-risk lesions (3p and 9p retention). Addition of another 2 markers (loci on 4q/17p) further improved the risk prediction, with five-year progression rates of 3.1%, 16.3%, and 63.1% for the low-, intermediate-, and high-risk lesions, respectively. Compared with the low-risk group, intermediate- and high-risk groups had 11.6-fold and 52.1-fold increase in risk (P < 0.001). LOH profiles as risk predictors in the refined model were validated in the retrospective cohort. Multicovariate analysis with clinical features showed LOH models to be the most significant predictors of progression. LOH profiles can reliably differentiate progression risk for OPLs. Potential uses include increasing surveillance for patients with elevated risk, improving target intervention for high-risk patients while sparing a large number of low-risk patients from needless screening and treatment.

Cell transformation and the evolution of a field of precancerization as it relates to oral leukoplakia

Potentially malignant oral leukoplakias arise within precancerized epithelial fields consisting of cytogenetically altered keratinocytes at various stages of transformation. The evolution of a clone of keratinocytes culminating in a precancerous phenotype is a function of the number of mutagenic events, rather than the sequential order in which they occur. The altered molecular configurations of the transformed precancerous keratinocytes may confer upon them a growth advantage in relation to the unaltered neighbouring keratinocytes. Replicative clonal expansion of these keratinocytes results in the progressive replacement of the surrounding normal keratinocytes by the fitter clone or clones of altered cells. The precancerized oral epithelial field may have a clinically normal appearance and microscopically may be normal or may show dysplasia. Oral leukoplakias arising within a precancerized epithelial field in which the keratinocytes show DNA aneuploidy or loss of heterozygosity at certain specific chromosomal loci have the potential to progress to carcinoma. The pathogenic mechanisms that drive the carcinomatous transformation of oral leukoplakias, in which cytogenetic alterations in the keratinocytes cannot be detected, are unknown.

Dysplasia of the upper aerodigestive tract squamous epithelium

Dysplasia of the oral, laryngeal and oropharyngeal stratified squamous epithelia is a microscopically defined change that may occur in clinically identifiable lesions including erythroplakia, leukoplakia and erythroleukoplakia, lesions that convey a heightened risk for carcinomatous progression. Dysplastic lesions have been classified microscopically according to degree of cytologic atypia and changes in architectural patterns, usually on a three part or four part gradation scale. Vocal cord epithelial lesions are graded according to either the Ljubljana or the World Health Organization (WHO) system whereas oral dysplasias are generally classified according to WHO criteria. Cytologically atypical cells are considered to represent precancerous changes predicting an increase risk for carcinomatous transformation. Inter- and intra-rater reliability studies among pathologists have disclosed low correlation coefficients for four part grading systems, whereas improved agreement is achieved (kappa correlation values) using the Ljubljana systems. Evidence forwarded by some studies supports the prognostic value of progressively severe dysplastic changes for carcinomatous transformation; however, some studies indicate that the presence of a clinically defined lesion without microscopic evidence of dysplasia also connotes increased risk for carcinomatous transformation. Loss of heterozygosity (LOH) at 3p and 9p microsatellite domains, DNA ploidy analysis and nuclear image analyses may have predictive value as molecular and histomorphological biomarkers.

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.

A long-term follow-up study on the natural course of oral leukoplakia in a Swedish population-based sample

AIM

To assess the natural course of screening-detected oral leukoplakia (OL) among non-consulting individuals.

METHODS

A cohort of 555 individuals with OL, confirmed in 1973-1974 during a population-based survey, were followed through January 2002 via record linkages with nationwide and essentially complete registers. A sample of 104 drawn from the 297 surviving cohort members who still were living in the area in 1993-1995 was invited to a re-examination. Sixty-seven of them attended.

RESULTS

At the time of re-examination OL had disappeared in 29 (43%) individuals. There was a statistically significant association between cessation of/no smoking habits in 1993-1995 and the disappearance of OL. Never/previous daily smokers were thus over-represented among individuals whose OL had disappeared compared to those with persisting OL [n = 23 (82%) vs. n = 18 (47%), P < 0.01]. Eighteen (78%) of the twenty three non-smokers with disappearing OL had quit after the initial examination. One man and two women developed oral cancer during follow-up while 0.7 and 0.07, respectively, were expected.

CONCLUSION

Smoking cessation was associated with an increased disappearance of OL. Hence, at least one-fourth had lesions that could be classified as tobacco-related. Small observed and expected numbers prohibited firm conclusions about a possible excess risk of developing oral cancer.

The results of CO2 laser surgery in patients with oral leukoplakia: a 25 year follow up

Oral leukoplakia is an important premalignant lesion of the oral mucosa. We treat this lesion prophylactically with CO2 laser evaporation. In the period from 1976 to 2001, a group of 200 patients with 282 oral leukoplakias were treated by CO2 laser evaporation. In a follow up period of 1-219 months (mean 52), 251 treated leukoplakias (89.0%) did not show a recurrence. Twenty eight (9.9%) local recurrences were observed in 5 to 168 months after treatment. Three (1.1%) squamous cell carcinoma, occurred in the treated area respectively 7, 17 and 19 month after CO2 laser evaporation. This large study with a long follow up shows that laser treatment is a good prophylactic treatment for oral leukoplakia.

Pooled estimate of world leukoplakia prevalence: a systematic review

This study was aimed at estimating the pooled global leukoplakia prevalence using both well-designed studies, which were too few to be representative of the world situation, and less valuable studies. The inverse variance weighting and the random effect methods were used. The latter is based on the principle that if primary studies are heterogeneous, the between-study variance is higher than zero, and its effect must be taken into account in choosing the weighting scheme. The robustness of the estimates was assessed by means of sensitivity analyses. Including 23 primary studies from all over the world published between 1986 and 2002, the point estimates were 1.49% (inverse variance, 95% confidence interval 1.42%-1.56%) and 2.60% (random effect, 95% confidence interval 1.72%-2.74%). The high between-study heterogeneity and the sensitivity analyses suggested that the second estimate was more reliable. Leukoplakia was significantly more prevalent among males (prevalence ratio 3.22), but no difference was found between geographical areas and between younger and older adults. Using these data, the crude annual oral cancer incidence rate attributable to leukoplakia would be between 6.2 and 29.1 per 100000, thus suggesting that the global number of oral cancer cases is probably underreported.

Immunohistochemical study of syndecan-1 down-regulation and the expression of p53 protein or Ki-67 antigen in oral leukoplakia with or without epithelial dysplasia

BACKGROUND

Leukoplakia is an oral pre-cancerous lesion that sometimes develops into squamous cell carcinoma. Therefore, leukoplakia with epithelial dysplasia is useful for studying carcinogenesis at the cellular level. The purpose of this study was to evaluate a potential association between the loss of syndecan-1 expression and the expression of p53 protein and Ki-67 antigen, and to identify reliable markers for predicting malignant changes in oral leukoplakia with epithelial dysplasia.

METHODS

Changes in the expression of syndecan-1, p53, and Ki-67 were examined immunohistochemically in 43 cases of oral leukoplakia with or without epithelial dysplasia. The subjects were categorized as: none, 13 cases; mild dysplasia, 5 cases; moderate dysplasia, 17 cases; and severe dysplasia, 8 cases. The expression of these molecules in normal oral epithelia (22 cases) was also investigated.

RESULTS

Strong syndecan-1 expression was observed on the surface of keratinocytes in normal epithelium. Immunopositivity was lost gradually as the extent of epithelial dysplasia increased. In normal epithelium, p53 and Ki-67 appeared mainly in the basal cell layer, while they were more widely distributed in leukoplakia. Specifically, significant changes were observed in the labeling index of p53 and Ki-67 in leukoplakia as epithelial dysplasia progressed from mild to moderate or severe.

CONCLUSION

Our results reveal that overexpression of p53 protein and Ki-67 antigen, and down-regulation of syndecan-1 expression in the lower part of the epithelium, are associated with dysplastic changes. Therefore, the down-regulation of syndecan-1 expression may be the most important reliable marker for dysplastic changes.

Oral epithelial dysplasia: clinical characteristics of western European residents

To detail the clinical presentation of oral epithelial dysplasia in a large cohort of residents in western Europe. Descriptive statistical analysis of the data were calculated using chi-square and Fisher's exact tests. Oral epithelial dysplasia manifested typically as a white or mixed red and white lesion on the tongue, buccal mucosa or floor of mouth. The peak age of presentation of oral epithelial dysplasia was the 6th decade. Most clinically detected lesions had only mild oral epithelial dysplasia. Although uncommon, lesions with severe dysplasia were most likely to arise on the floor of mouth or lateral border of tongue. Oral epithelial dysplasia is likely to manifest as a solitary white patch, but it is not possible to accurately predict the likely degree of dysplasia from the clinical features of such lesions.

Histopathological and immunohistochemical study of malignant transformation of oral leukoplakia, with special reference to apoptosis-related gene products and proliferative activity

OBJECTIVE

To examine the frequency of apoptosis in oral leukoplakia and its relationship with pathological parameters, including Ki-67 expression, and with the expression of p53, Bcl-2 and Bax proteins. MATERIAL AND MEHODS: Clinical, histopathological and immunohistochemical studies were carried out and the terminal deoxynucleotide transferase-mediated dUTP nick-end labeling method was used to verify the apoptosis and its mechanism of genetic control of the development, progression and promotion of lesions. The material consisted of five normal mucosal epithelia. six leukoplakias without malignant transformation and seven leukoplakias with malignant transformation. Based on counts of 10 fields at a magnification of x 400, mitotic, apoptotic and Ki-67 indices were calculated, and p53, Bcl-2 and Bax expressions were recorded.

RESULTS

The peak of the mitotic and Ki-67 indices and p53 expression shifted basally, possibly as a result of malignant transformation, whilst the peak of apoptosis and the expression of apoptotic-related proteins in oral leukoplakia showed no transformation.

CONCLUSION

The frequent expression of Bcl-2 in oral leukoplakia with malignant transformation combined with the reduction in the number of apoptotic cells indicated that malignancy occurred as a result of the avoidance of apoptosis. In addition, high levels of Bax expression in oral leukoplakia without malignant transformation indicated that the Bcl family may play a role in the progression of the disease.

Potentially malignant oral lesions in Northern Ireland: size (extent) matters

OBJECTIVES

We examined clinical parameters of patients from Northern Ireland with potentially malignant lesions (PML) to determine association with development of intraoral squamous cell carcinoma (SCC).

DESIGN

retrospective, cross-sectional, population-based, clinically validated, laboratory-verified.

SUBJECTS AND METHODS

All patients who had more than one incisional oral mucosal biopsy diagnosed from 1975-1991 were abstracted from a database of all PML and SCC and their clinical records and biopsies reviewed. Patients were excluded if there was priorlsynchronous SCC or radiotherapy, frictional keratosis or lichen planus, missing clinical records/biopsy material or follow-up of <24 months. From the 50 suitable patients, gender, age, smoking status, site, clinical appearance and extent of lesion(s), treatment and year of diagnosis were recorded. Patients who developed SCC from PML were compared with those who did not.

RESULTS

Squamous cell carcinoma occurred significantly more often in patients with single rather than multiple PML, those with 'non-homogenous' PML and in patients diagnosed prior to 1980. In Cox's survival analysis, only the clinical extent was predictive of SCC.

CONCLUSIONS

Of all the features considered in our series, size (extent) was the most important clinical factor in determining the risk of future SCC in PML, particularly when several adjacent anatomical sites were affected.

Investigation of environmental factors for diagnosing malignant potential in oral epithelial dysplasia

A study was conducted in rats with early tongue carcinoma induced by 4-nitroquinoline 1-oxide (4NQO), in order to investigate the early diagnosis of malignant potential of epithelial dysplasia. The rat tongue lesions were classified by their severity into three groups corresponding to early cancer, dysplasia and no change. The grade of epithelial changes was determined according to 13 items of WHO Epithelial Dysplasia Criteria. The expression levels of p53 and Bcl-2 proteins were detected immunohistochemically, and apoptotic cells were detected using the TUNEL method. In addition, a p53 mutation by lesions was detected. The expression ratio of p53 protein was high in dysplasia, and the ratio of Bcl-2 protein was high in early cancer and dysplasia. The TUNEL-positive cells were observed primarily in the granular layers of the no change cells, and their numbers decreased as the cells shifted to the early cancer stage. The p53 mutation was detected using a microdissection method in dysplasia, where it was found in three out of nine lesions. All the mutations in dysplasia detected were on the same codon that was found to be mutated in the early cancer. These results indicate that the association between the p53 mutation and histological changes in carcinogenesis epithelial dysplasia is strong, and that both the identification of p53- and Bcl-2-positive epithelium, and decrease in the TUNEL positive ratio, were useful for the diagnosis of the malignant potential of precancerous lesions.

Carbon dioxide laser evaporation of leukoplakia of the lower lip: a retrospective evaluation

The purpose of this study was the retrospective evaluation of the treatment results of CO2 laser evaporation for 27 cases of leukoplakia of the lip. The data were derived from 23 patients who presented with leukoplakia of the lower lip during the period 1978-96. Four patients developed a second primary leukoplakia of the lip resulting in 27 cases of leukoplakia. All lesions were treated with a CO2 laser equipped with an operation microscope and micromanipulator. Short-term evaluation showed complete epithelialisation 4 weeks after CO2 laser evaporation; there was minimal scar formation and no subsequent interference with normal lip function. During long-term evaluation, four recurrences (14.8%) were diagnosed which developed between 5 and 31 months after treatment, these were retreated with CO2 laser evaporation. There was no development of squamous cell carcinoma in the CO2 laser-treated area. Selective removal of affected epithelium with minimal damage to surrounding structures is possible using CO2 laser evaporation, followed by excellent wound healing and good functional result. Treatment can be performed under local anaesthesia on an outpatient basis. The recurrence rate is low compared with the recurrence rate after surgical excision. Therefore, CO2 laser evaporation is considered a reliable and effective treatment modality for leukoplakia of the lip.

Oral cancer in the UK: to screen or not to screen

Although oral squamous cell carcinoma accounts for only a small proportion of malignant neoplasms in the UK, oral cancer incidence and mortality rates have been rising in recent years. The natural history of oral cancer is not adequately understood at present and there is very little information about the epidemiology of precancerous lesions in the UK. There are also insufficient data to provide firm evidence that the percentage of cases arising de novo is greater in the UK and the Western world as compared to the Indian subcontinent. Screening for oral cancer by visual examination is simple, inexpensive and causes little discomfort; however, there is no evidence for the effectiveness of screening for oral cancer either in reducing mortality from the disease or in reducing the incidence of invasive disease by detection and treatment of precancerous lesions. There is currently insufficient evidence to recommend population screening for oral cancer in the UK. Measures aimed at primary prevention of the disease may be a more feasible method of disease control at present.

Flow cytometric analysis of nuclear DNA content in oral leukoplakia: relation to clinicopathologic findings

DNA ploidy of 50 biopsy specimens of oral leukoplakia was investigated by flow cytometry, and the results were compared with the clinicopathologic appearances. The aneuploidy rate of the leukoplakias was 17/50 (34%), and the mean DNA index (DI) of the aneuploid lesions was 1.22, with a range from 0.70 to 1.84. The incidence of the aneuploidy was significantly (P < 0.01) higher in nonhomogeneous leukoplakias (11/18) than in homogeneous lesions (6/32). The aneuploidy rate of the severely dysplastic leukoplakias (11/17) was significantly higher than those of the mildly dysplastic (4/22; P < 0.01) and the nondysplastic (2/11; P < 0.02) lesions. A significant (P < 0.01) difference in the aneuploidy rate was also observed between tongue (12/23) and gingival (2/18) leukoplakias.

p53 expression in the carcinogenesis in the oral mucosa

Hyperplastic lesions of the oral mucosa such as leukoplakia and oral lichen planus can eventually develop into squamous cell carcinomas. In the clinical treatment of these lesions it would be very important to be able to predict the biological behaviour of an individual lesion. In 64 hyperplastic lesions and 85 squamous cell carcinomas of the oral mucosa, the expression of the mutant tumor suppressor gene p53 was investigated. A positive correlation was seen between the expression of the mutant tumor suppressor gene p53 and the grade of dysplasia of the lesions.

p53 and PCNA expression in carcinogenesis of the oropharyngeal mucosa

Hyperplastic lesions of the oral mucosa such as leukoplakia and oral lichen planus can eventually develop into squamous cell carcinomas (SCC) and provide an excellent model for multistage carcinogenesis. The development of carcinomas is assumed to be the result of interaction of genetic factors, locally applied carcinogens and immunological unresponsiveness. The purpose of this study was, therefore, to determine the role of alterations of the tumour suppressor gene p53, and the proliferation status of the lesions determined by PCNA expression. We investigated p53 and PCNA expression in 265 tissue sections of normal mucosa, premalignant, malignant and metastatic lesions of the oral mucosa by immunohistology. Quantitative analysis showed a gradual increase in PCNA expression from normal mucosa to moderately differentiated SCC. p53 expression was detectable in benign premalignant lesions. The increase in the number of p53-positive biopsies was correlated with the dysplasia and loss of differentiation in the premalignant and malignant lesions.

Keratin profiles of normal and malignant oral mucosa using exfoliative cytology

AIMS

To assess keratin profiles from smears of malignant and contralateral normal oral mucosa as part of the development of a screening procedure for oral cancer based on exfoliative cytology.

METHODS

Smears were taken from oral cancers (confirmed by biopsy) and from the contralateral site of 20 patients. Using a panel of antikeratin antibodies, the keratins expressed by these cells were identified using a standard immunocytochemical technique (Vectastain) and assessed on a 3 point scale.

RESULTS

Using chi 2 analysis, noticeable differences between the keratin profiles for malignant mucosal smears compared with the contralateral mucosal smears were found. This was particularly evident for the simple epithelial keratins.

CONCLUSION

Individual keratins can be identified in smears from oral cancers. The identification of simple epithelial keratins seem to be the best keratin markers associated with malignancy. Their detection within smears from oral lesions could be valuable in the early diagnosis of oral cancer.

Risk of preneoplastic and neoplastic events in operated oral leukoplakias

We retrospectively analysed 167 consecutive patients with oral leukoplakias operated on by CO2 laser resection in the Day Hospital of the Istituto Nazionale Tumori in Milan from January 1981 to December 1988, with post-operative histological examination negative for cancer. Within 5 years there were 69 patients with at least one unfavourable event. First unfavourable events were: 31 local relapses, 27 new leukoplakias, 5 oral carcinomas and 6 other neoplasms elsewhere. To identify possible prognostic factors we recorded age, sex and history of previous oral leukoplakias or head and neck cancers; also number, site, size and type of lesion; as well as tobacco and alcohol consumption and oral hygiene. The Cox regression model was employed to compare disease-free survival between different patient groups, both by univariate and multivariate analysis. From this analysis it emerges that age of operated patients and size of resected lesion are significantly predictive for development of relapses, new leukoplakias and carcinomas.

Prevention of local relapses and new localisations of oral leukoplakias with the synthetic retinoid fenretinide (4-HPR). Preliminary results

This paper analyses preliminary results of a randomised chemoprevention trial in patients surgically treated for oral leukoplakia started in 1988 at the Istituto Nazionale Tumori of Milan with the synthetic retinoid N-(4-hydroxyphenyl)-retinamide (4-HPR). To date 115 patients have been randomised, after surgical excision of oral leukoplakia, to receive 200 mg 4-HPR daily for 52 weeks versus no intervention. 80 patients completed the 1-year intervention, 41 in the control group and 39 in the 4-HPR group. During this period 12 local relapses or new lesions occurred in the control group and three in the 4-HPR group. Only 5 patients interrupted the intervention because of toxicity. No impaired dark adaptation was observed. It is concluded that 4-HPR is well tolerated and seems efficacious in preventing relapses and new localisations during the treatment period. This promising trend needs further confirmation.

DNA analysis of oral leukoplakia by flow cytometry

DNA ploidy of 19 oral leukoplakias with and without epithelial dysplasia was investigated and the results were compared with 11 normal gingival biopsies, 14 oral benign tumours and 50 oral squamous cell carcinomas. The results suggest a possible relationship between DNA aneuploidy and oral leukoplakias or squamous cell carcinomas, as 32% of the oral leukoplakias and 48% of the oral squamous cell carcinomas were aneuploid although all the normal gingival biopsies and the benign oral tumours examined were diploid. No significant relationship was observed, however, between DNA ploidy and epithelial dysplasia in the leukoplakias.

Ultrastructural examination of experimentally induced premalignant lesions

Lesions induced in hamster cheek pouch using dimethylbenz(alpha)anthracene were studied by transmission electron microscopy and compared with normal tissue. Features regarded as suggestive of progression towards malignancy were: increased numbers of membrane-bound vesicles in basal cells, gaps in the lamina densa associated with widening of the lamina lucida and an irregular epithelial-connective tissue junction, the presence of cerebriform cells and frequent close association of 2 or more intra-epithelial cells (lymphocytes, cerebriform cells, Langerhans cells).