Malignant transformation of oral potentially malignant disorders in Taiwan: An observational nationwide population database study

Premalignant lesions of the oral cavity: a narrative review of factors and mechanisms of transformation into cancer

Oral squamous cell carcinoma (OSCC) is the most common type of head and neck cancer. The development and progression of OSCC are closely linked to various aetiological factors. Early signs of OSCC may manifest as oral lesions, genetic abnormalities, and chronic inflammation. Lesions with dysplastic features have a high risk of malignant transformation into OSCC. Moreover, dysplastic lesions are characteristic of many oral potentially malignant disorders (OPMDs). Currently, there is no unified standard of treatment for OPMD patients, due to the variability in risk factors and mechanisms of transformation. Therefore, it is essential to detect and manage OPMDs at an early stage in order to prevent their malignant transformation into OSCC. This necessitates analysing OPMD mechanisms to identify objective markers for predicting the risk of malignant transformation. The aim of this review was to describe the process of OPMD transformation into OSCC under the influence of environmental, immune, microbiome, and molecular factors.

State of art of micronuclei assay in exfoliative cytology as a clinical biomarker of genetic damage in oral carcinogenesis: A systematic review and meta-analysis

Oral squamous cell carcinoma (OSCC) is the most common oral malignancy, often preceded by oral potentially malignant disorders (OPMDs). Currently, no clinical biomarker exists to predict malignancy, necessitating OPMD follow-up. Habits and environmental factors, such as smoking, and alcohol consumption, influence OSCC onset. Increased micronuclei (MNs) formation has been observed in the development of OSCC. Non-invasive diagnostic tests like exfoliative cytology offer painless and regular monitoring options. This study evaluates the impact of tobacco, alcohol, and pesticide exposure on MNs occurrence in exfoliative cytology-collected oral mucosal cells, assessing their potential as non-invasive biomarker for OSCC development prediction and monitoring in high-risk patients. Despite results from this meta-analysis supporting the existence of a stepwise increase from controls to patients with OPMD to OSCC, the translation of these findings into clinical practice is limited due to intra- and inter-individual heterogeneity, as well as methodological variability in MNs quantification. Various factors contribute to this heterogeneity, including demographic variables, methodological variability of different laboratories, staining techniques, sample collection location, and patient characteristics. All these points were discussed to provide further insights and improve standardization for future studies.

Precursor Lesions, Overdiagnosis, and Oral Cancer: A Critical Review

Despite the profession placing great emphasis on oral potentially malignant disorders (OPMDs) as a gateway for early recognition and consequently better outcomes for oral cancer, the death rates for lip and oral cavity cancer have remained stagnant for three decades. Evidence shows that only a small fraction of oral cancers are in fact preceded by OPMDs, and that most OPMDs have an annual transformation rate of less than 1%. As OPMDs encompass a very heterogeneous group of oral conditions, it could be argued that only patients with oral mucosal diseases bearing a substantial risk of malignant transformation warrant close surveillance and treatment, these include proliferative leukoplakia, erythroplakia, non-homogeneous leukoplakia, as well as diseases presenting with severe dysplasia at biopsy. In this narrative review, I discuss the intricate epidemiology of the malignancies that we colloquially refer to as oral cancer, explore the limitations of focusing on OPMDs to reduce the incidence and mortality of oral cavity cancer, and argue that a may-be cancer label represents overdiagnosis for most OPMDs.

Evaluation of CYP1B1, oxidative stress and phase II detoxification enzyme status in oral cancer progression model

Background

Tobacco is one of the main etiological factors for oral squamous cell carcinoma (OSCC) and oral potentially malignant disorders (OPMD). CYP1B1 is an enzyme which plays a major role in the phase I detoxification of tobacco, the byproducts of which are subsequently detoxified by phase II enzymes Glutathione S Transferase (GST). We attempted to evaluate the L432V polymorphism and tissue expression of CYP1B1, along with the oxidant-antioxidant status in OSCC progression model.

Method

ology: Tissue biopsies and blood samples were collected from the subjects; L432V polymorphism was evaluated by TaqMan RT-PCR, immunohistochemistry was performed on the tissue sample using CYP1B1 polyclonal primary antibody and Allred quick scoring system was used to evaluate the stained slides. Malonaldehyde (MDA) and GST activity were measured spectrophotometrically to assess oxidative-antioxidative status.

Results

When the L432V polymorphism was analyzed, it was observed that in oral epithelial dysplasia (OED) and OSCC, CG was more common than GG genotype. Highest mean Allred score was observed in tobacco users (6.27), highest GST activity was seen in oral epithelial dysplasia (5.006 U/ml) and highest MDA activity was observed in OSCC (1553.94 nm/ml).

Conclusion

Tobacco users with CG and GG genotypes are at equal risk of developing oral epithelial dysplasia or OSCC and L432V polymorphism does not appear to increase the risk of malignant transformation in oral epithelial dysplasia. Moreover, tobacco users with GG genotype and tissue expression of CYP1B1 may be at a greater risk of oxidative damage.

Prevalence and Malignant Transformation Rate of Oral Erythroplakia Worldwide - A Systematic Review

Background

To determine the characteristics of oral erythroplakia (OE) on a global scale, it is important to analyse and evaluate findings from various studies conducted across multiple geographical locations.

Objectives

This review was conducted to determine the prevalence and malignant transformation rate (MTR) of OE.

Data Sources

A systematic search was performed to identify studies reporting the prevalence and MTR of OE across various databases - PubMed, Web of Science, Google Scholar, Elsevier and ScienceDirect without any restriction for the time of publication.

Study Eligibility Criteria

This review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines, and the protocol was registered in the PROSPERO database (ID: CD42023395215).

Results

The prevalence rate of OE reported across the studies ranged from 0.04% to 1.14% with a mean of 0.25 + 0.002%. The MTRs reported across the studies included ranged from 2.6% to 65% with a mean of 30 ± 0.2%.

Limitations and Conclusions

Based on the findings from the present review, it can be concluded that while the range of MTRs of OE varies widely across different geographical locations, the average rate can be considered 30%. The review also identified a need for conducting more studies on the prevalence rates as well as longitudinal studies assessing the MTR across different regions.

Atypical Squamous Verrucous Lesions of the Oral Cavity: Challenges in Interpretation of Small Incisional Biopsies

BACKGROUND

Squamous verrucous proliferative lesions of oral cavity can pose a diagnostic challenge for the general pathologist, especially on small biopsies. The superficial nature of incisional biopsies and inconsistent histologic terminologies used for these lesions contribute to often-discrepant clinical diagnosis, resulting in delayed treatment. This study aims to explore the proliferative squamous lesions of oral cavity, correlate biopsy & resection diagnoses, and evaluate possible reasons for discrepant diagnosis (if any).

DESIGN

A retrospective review of oral verrucous squamous lesions was undertaken. Pathology database was searched for oral cavity biopsies from January2018 through August2022 with the keywords: atypical, verrucous, squamous, and proliferative. Cases with follow-up were included in this study. A blinded review of the biopsy slides was performed and documented by a single head and neck pathologist. Demographic data, biopsy and final diagnosis were recorded.

RESULTS

Twenty-three cases met criteria for inclusion. The mean patient age was 61.1 years with a male: female ratio of 1.09. Most frequent site was lateral border of tongue (36%) followed by buccal mucosa and retromolar trigone. The most common biopsy diagnosis was "Atypical squamoproliferative lesion, excision recommended" (n = 16/23, 69%) with 13/16 showing conventional squamous cell carcinoma (SCC) on follow-up resection. 2/16 atypical cases underwent repeat biopsy for confirmation of diagnosis. Overall, conventional SCC was the most prevalent final diagnosis (73%, n = 17), followed by verrucous carcinoma (17%, n = 4). On slide review, six initial biopsies were reclassified as SCC, while one final diagnosis was reclassified as a hybrid carcinoma (on resection specimen). Diagnostic concordance (biopsy and resection) was observed in three cases, all three were recurrences. The primary reasons for discrepant diagnosis on initial biopsies were found to be 1. Obscuring inflammation, 2. Superficial biopsies, and 3. Under recognition of morphologic features (e.g., tear shaped rete, loss of polarity, dyskeratotic cells, paradoxical maturation) that help differentiate dysplasia from reactive atypia.

CONCLUSION

This study highlights the rampant interobserver variability in diagnosis of oral cavity squamous lesions and emphasizes importance of identifying morphologic clues that can aid in correct diagnosis, thereby helping in adequate clinical management.

Malignant transformation rate of oral leukoplakia in the past 20 years: A systematic review and meta-analysis

BACKGROUND

This meta-analysis aimed to assess the rate of malignant transformation (MT) of oral leukoplakia (OL) and to study potential risk factors for the MT of OL into oral squamous cell carcinoma (OSCC).

METHOD

We performed a bibliographic search on nine electronic databases, including PubMed, MEDLINE, and Wanfang Data, for data on the MT rate of OL. Possible risk factors were calculated using Comprehensive Meta-Analysis and Open Meta [Analyst] software.

RESULTS

The pooled proportion of OL MT for the total population described in the 26 selected studies was 7.20% (95% confidence interval: 5.40-9.10%). Nonhomogeneous type lesions, higher grades of dysplasia, the location of the lesion (tongue and multifocal), and female sex had significant effects on the MT of OL.

CONCLUSION

OL tended to develop into OSCC (7.2%), and those with significant MT risk factors should be subjected to regular follow-up and observation. However, we require large-scale prospective studies to validate these results, together with unified clinicopathological diagnostic criteria, standardized risk factor recording/assessment methods, and long-term follow-up guidelines.

The Way to Malignant Transformation: Can Epigenetic Alterations Be Used to Diagnose Early-Stage Head and Neck Cancer?

Identifying and treating tumors early is the key to secondary prevention in cancer control. At present, prevention of oral cancer is still challenging because the molecular drivers responsible for malignant transformation of the 11 clinically defined oral potentially malignant disorders are still unknown. In this review, we focused on studies that elucidate the epigenetic alterations demarcating malignant and nonmalignant epigenomes and prioritized findings from clinical samples. Head and neck included, the genomes of many cancer types are largely hypomethylated and accompanied by focal hypermethylation on certain specific regions. We revisited prior studies that demonstrated that sufficient uptake of folate, the primary dietary methyl donor, is associated with oral cancer reduction. As epigenetically driven phenotypic plasticity, a newly recognized hallmark of cancer, has been linked to tumor initiation, cell fate determination, and drug resistance, we discussed prior findings that might be associated with this hallmark, including gene clusters (11q13.3, 19q13.43, 20q11.2, 22q11-13) with great potential for oral cancer biomarkers, and successful examples in screening early-stage nasopharyngeal carcinoma. Although one-size-fits-all approaches have been shown to be ineffective in most cancer therapies, the rapid development of epigenome sequencing methods raises the possibility that this nonmutagenic approach may be an exception. Only time will tell.

Sprouty 4 expression in human oral squamous cell carcinogenesis

Background/purpose

Reviewing literature, sprouty 4 (SPRY4) has not been studied in human oral squamous cell carcinomas (OSCCs). The study aimed to examine SPRY4 expression in human oral squamous cell carcinogenesis.

Materials and methods

A total of 95 OSCCs, 10 OPMDs with malignant transformation (MT), 17 OPMDs without MT, and six normal oral mucosa (NOM) samples were recruited for immunohistochemical staining; three OSCC tissues with normal tissue counterpart NOM were employed for Western blotting. Three human oral cancer cell lines (OCCLs), an oral precancer cell line (dysplastic oral keratinocyte, DOK), and a primary culture of normal oral keratinocytes (HOK) were used for Western blotting; OCCLs and HOK were employed for real-time quantitative reverse transcription-polymerase chain reaction. OCCLs were evaluated in terms of proliferation, migration, and invasion assays.

Results

SPRY4 protein expression was significantly increased in OSCCs compared with NOM. Protein and mRNA SPRY4 expression in OCCLs were significantly elevated compared with HOK. Significant increases in the degrees of proliferation, migration, and invasion were noted in OCCLs with SPRY4 siRNA transfection compared with those without transfection. SPRY4 protein level was increased in OPMD with MT compared to OPMD without MT. SPRY4 protein was significant increase in DOK in comparison with HOK. SPRY4 protein expression was significantly increased from NOM and OPMD without MT to OSCC. SPRY4 protein expression in OCCLs was significantly enhanced compared with DOK and HOK respectively.

Conclusion

Our results indicate that SPRY4 expression is possibly involved in human oral squamous cell carcinogenesis.

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

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

Malignant transformation of oral potentially malignant disorders in Taiwanese indigenous peoples: A nationwide retrospective cohort study

Malignant transformation of oral potentially malignant disorders (OPMDs) is a potential cause of oral cancer. Currently, there is no research investigating the rate of malignant transformation of OPMDs into oral cancer in indigenous Taiwanese peoples. This study aimed to retrospectively investigate whether ethnicity (indigenous vs non-indigenous people) plays a role in increasing the malignant transformation rate of OPMDs into oral cancer. This study used data from the oral mucosal screening database and the Cancer Registry File, both of which originated from the National Health Insurance Research Database. We matched the baseline characteristics to control for confounding factors between indigenous peoples and non-indigenous peoples (17,768 indigenous subjects vs 71,072 non-indigenous subjects; 1:4 match) and compared the 2 cohorts. After matching for confounding factors such as age, sex, habits, and OPMD subtype, the malignant transformation rate was not statistically higher for indigenous people than for non-indigenous people. We also discovered that indigenous people with oral verrucous hyperplasia might have a higher chance of malignant transformation into oral cancer than the non-indigenous cohort. We conclude that ethnicity is not a risk factor for the malignant transformation of OPMDs into oral cancer; however, indigenous people with oral verrucous hyperplasia need to pay special attention and are suggested to undergo regular follow-ups for the occurrence of oral cancer.

Automated detection of premalignant oral lesions on whole slide images using convolutional neural networks

INTRODUCTION

Oral epithelial dysplasia (OED) is a precursor lesion to oral squamous cell carcinoma, a disease with a reported overall survival rate of 56 percent across all stages. Accurate detection of OED is critical as progression to oral cancer can be impeded with complete excision of premalignant lesions. However, previous research has demonstrated that the task of grading of OED, even when performed by highly trained experts, is subject to high rates of reader variability and misdiagnosis. Thus, our study aims to develop a convolutional neural network (CNN) model that can identify regions suspicious for OED whole-slide pathology images.

METHODS

During model development, we optimized key training hyperparameters including loss function on 112 pathologist annotated cases between the training and validation sets. Then, we compared OED segmentation and classification metrics between two well-established CNN architectures for medical imaging, DeepLabv3+ and UNet++. To further assess generalizability, we assessed case-level performance of a held-out test set of 44 whole-slide images.

RESULTS

DeepLabv3+ outperformed UNet++ in overall accuracy, precision, and segmentation metrics in a 4-fold cross validation study. When applied to the held-out test set, our best performing DeepLabv3+ model achieved an overall accuracy and F1-Score of 93.3 percent and 90.9 percent, respectively.

CONCLUSION

The present study trained and implemented a CNN-based deep learning model for identification and segmentation of oral epithelial dysplasia (OED) with reasonable success. Computer assisted detection was shown to be feasible in detecting premalignant/precancerous oral lesions, laying groundwork for eventual clinical implementation.

Single-Cell RNA Sequencing Analysis for Oncogenic Mechanisms Underlying Oral Squamous Cell Carcinoma Carcinogenesis with Candida albicans Infection

Oral squamous cell carcinoma (OSCC) carcinogenesis involves heterogeneous tumor cells, and the tumor microenvironment (TME) is highly complex with many different cell types. Cancer cell-TME interactions are crucial in OSCC progression. Candida albicans (C. albicans)-frequently pre-sent in the oral potentially malignant disorder (OPMD) lesions and OSCC tissues-promotes malignant transformation. The aim of the study is to verify the mechanisms underlying OSCC car-cinogenesis with C. albicans infection and identify the biomarker for the early detection of OSCC and as the treatment target. The single-cell RNA sequencing analysis (scRNA-seq) was performed to explore the cell subtypes in normal oral mucosa, OPMD, and OSCC tissues. The cell composi-tion changes and oncogenic mechanisms underlying OSCC carcinogenesis with C. albicans infec-tion were investigated. Gene Set Variation Analysis (GSVA) was used to survey the mechanisms underlying OSCC carcinogenesis with and without C. albicans infection. The results revealed spe-cific cell clusters contributing to OSCC carcinogenesis with and without C. albicans infection. The major mechanisms involved in OSCC carcinogenesis without C. albicans infection are the IL2/STAT5, TNFα/NFκB, and TGFβ signaling pathways, whereas those involved in OSCC carcinogenesis with C. albicans infection are the KRAS signaling pathway and E2F target down-stream genes. Finally, stratifin (SFN) was validated to be a specific biomarker of OSCC with C. albicans infection. Thus, the detailed mechanism underlying OSCC carcinogenesis with C. albicans infection was determined and identified the treatment biomarker with potential precision medicine applications.

Exploiting salivary miR-375 as a clinical biomarker of oral potentially malignant disorder

Background/purpose

Oral potentially malignant disorder (OPMD) is an important premalignancy worldwide. MicroRNAs (miRNAs) are endogenously expressed non-coding RNAs that regulate the post-transcriptional levels of targeted mRNAs. MiRNA-375 (miR-375) is markedly downregulated in oral carcinoma tissues and plays an oncogenic role in oral carcinogenesis. We explored the potential of the deregulated salivary miR-375 levels in OPMD patients.

Materials and methods

. We analyzed the levels of miR-375 in the saliva of patients with OPMD (n = 45) and healthy controls (n = 24) by quantitative RT-PCR. The cell lysates and supernatants were treated with the miR-375 mimic and inhibitor.

Results

Salivary miR-375 levels were decreased markedly in the patients with OPMD, compared with the controls. OPMD patients with non-dysplasia showed a higher abundance of miR-375 in the saliva than dysplasia patients, suggesting that salivary miR-375 is a more sensitive marker for OPMD. Patients with malignant transformation during the follow-up period showed lower expression of saliva miR-375 than the others. MiR-375 expression was markedly decreased by treatment with the miR-375 inhibitor, and the supernatants of both NHOK and SAS cells showed a corresponding decline in miR-375 expression.

Conclusion

Our results indicate the potential application of salivary miR-375 as a biomarker for the detection and long-term follow-up of OPMD.

Outpatient Dental Treatment Expenditure for Patients with Oromaxillofacial Cancer: A Cohort Study in Taiwan

The information on the outpatient expenditure of patients with oromaxillofacial cancer is minimal. This study aimed to compare the average annual expenditure on dental treatment for these patients 5 years before and 5 years after oromaxillofacial cancer diagnosis. In this study, 7731 patients who received oromaxillofacial cancer diagnosis in 2005 were selected from the Registry of Catastrophic Illness Database as the case-cohort. In the control cohort, 38,655 people without cancer were selected from the National Health Insurance Research Database, with the case–control ratio being 1:5. All participants were observed for 5 years before diagnosis and 5 years after diagnosis. The conditional logistic regression model was used to determine the odds ratios of annual expenditures incurred by participants in the case-cohort. The measurement results indicated that in the oromaxillofacial cancer cohort, the average annual dental expenditure levels at 1, 2, 3, 4, and 5 years after diagnosis were US $97.34, US $77.23, US $109.65, US $128.43, and US $128.03 and those at these years before diagnosis were US $37.52, US $32.10, US $31.86, US $29.14, and US $29.35, respectively. In conclusion, the average annual expenditure on the dental treatment of oromaxillofacial cancer patients after five years of diagnosis was increased compared to five years before diagnosis.

Development and validation of a nomogram prediction model for malignant transformation of oral potentially malignant disorders

OBJECTIVE

Oral potentially malignant disorders have increased the risk of oral squamous cell carcinoma. This study developed a nomogram model to assess the risks of malignant transformation of oral potentially malignant disorders.

MATERIALS AND METHODS

A retrospective analysis of patients diagnosed with oral potentially malignant disorders confirmed by pre-treatment biopsy was performed between 2010 and 2017 at the Peking University Hospital of Stomatology. The candidate risk factors for malignant transformation were screened from clinicopathological variables using Cox and stepwise regression analyses. The nomogram model was constructed based on the regression results and was validated through receiver operating characteristic curves and calibration curves. Decision curve analysis was used to estimate clinical usefulness.

RESULTS

A total of 6964 cases of oral potentially malignant disorders were assessed. The malignant transformation rate of oral potentially malignant disorders was 2.00%. Risk factors (age, site, kind of oral potentially malignant disorder, existence of dysplasia and its grade, and other cancers) derived from the regression analyses were entered into the nomogram model. Time-dependent receiver operating characteristic curve, calibration curve, and decision curve analyses showed high levels of predictive value and clinical relevance, although not for all oral potentially malignant disorders.

CONCLUSION

A specific dynamic nomogram could be adopted to predict the malignant transformation of oral potentially malignant disorders and implement interventions.

Aberrant miR-10b, miR-372, and miR-375 expression in the cytobrushed samples from oral potentially malignant disorders

Background/purpose

MicroRNA (miRNA) alterations play important roles in the neoplastic process of oral squamous cell carcinoma (OSCC). Upregulation of miR-10b and miR-372 and downregulation of miR-375 are frequent events in OSCC. The aberrances of these miRNAs in oral potentially malignant lesions (OPMD) were studied to determine their status during the establishment of OSCC.

Materials and methods

Cytobrushed sampling was used to collect epithelial cells from 11 OSCC and 34 OPMD lesions and matched normal mucosa. The expression levels of miR-10b, miR-372, and miR-375 were analyzed using quantitative reverse transcription polymerase chain reaction analysis. The clinical implications of these aberrances were further investigated.

Results

Both miR-10b and miR-372 were upregulated in OPMD, but only miR-10b expression was upregulated in OSCC comparing to control. miR-375 was downregulated in OPMD and tended to be downregulated in OSCC. Dysplastic OPMD could be distinguished based on miR-372 expression level; miR-375 expression levels facilitated discrimination between OPMD and OSCC. The combined analysis of miR-375 and miR-372 remarkably enhanced the accuracy of differentiating OPMD from OSCC.

Conclusion

Aberrant miR-10b. miR-372, and miR-375 expression occurs early during oral carcinogenesis. The detection of miR-372 and miR-375 expression using cytobrush samples may assist in differentiating between OPMD and OSCC.