Malignant Transformation Rate of Non-reactive Oral Hyperkeratoses Suggests an Early Dysplastic Phenotype

Cancer Precursor Syndromes and Their Detection in the Head and Neck

This article explores the multifaceted landscape of oral cancer precursor syndromes. Hereditary disorders like dyskeratosis congenita and Fanconi anemia increase the risk of malignancy. Oral potentially malignant disorders, notably leukoplakia, are discussed as precursors influenced by genetic and immunologic facets. Molecular insights delve into genetic mutations, allelic imbalances, and immune modulation as key players in precancerous progression, suggesting potential therapeutic targets. The article navigates the controversial terrain of management strategies of leukoplakia, encompassing surgical resection, chemoprevention, and immune modulation, while emphasizing the ongoing challenges in developing effective, evidence-based preventive approaches.

Oral epithelial dysplasia with lymphocytic immune response: clinicopathological characterisation of 44 cases

AIMS

Oral epithelial dysplasia (OED) often exhibits a lymphocytic/lichenoid immune response (LIR), imparting histological resemblance to lichenoid mucositis and rendering diagnosis challenging. The clinical appearances of OED and lichenoid inflammatory processes are generally divergent, presenting as well-demarcated hyperkeratotic plaques and diffuse white and/or red mucosal change with variably prominent Wickham striae, respectively. To date, clinicopathological characterisation of OED with LIR, including clinical/gross appearance, has not been depicted.

METHODS AND RESULTS

Cases of solitary OED with LIR for which a clinical photograph was available were identified in the authors' institutional files. Clinical and histological features were documented. In 44 identified cases, dysplasia was mild (19 of 44, 43.2%), moderate (19 of 44, 43.2%) and severe (six of 44, 13.6%). Clinically/grossly, all 44 cases (100.0%), presented as well-demarcated hyperkeratotic plaques lacking diffuse white-and-red mucosal change or Wickham striae. Histologically, OED with LIR exhibited numerous 'lichenoid' features beyond the lymphocytic band in the superficial lamina propria, including: leucocyte transmigration (38 of 44, 86.4%), spongiosis (37 of 44, 84.1%), Civatte/colloid bodies (36 of 44, 81.8%), basal cell degeneration (29 of 45, 65.9%), sawtooth rete ridges (11 of 44, 25.0%) and subepithelial clefting (7 of 44, 15.9%).

CONCLUSIONS

Virtually any lichenoid histological feature may be seen in OED with LIR, representing a significant diagnostic pitfall. The typical clinical appearance of OED with LIR is of a well-demarcated hyperkeratotic plaque, characteristic of keratinising dysplasia and devoid of lichenoid features. This suggests that pathologist access to clinical photographs during diagnostic interpretation of biopsied white lesions, which represents opportunity to perform gross examination of the disease process, may reduce interobserver variability and improve diagnostic accuracy in this challenging differential diagnosis.

Differences among oral carcinomas arising de novo from those associated with oral potentially malignant disorders: a systematic review and meta-analysis

OBJECTIVE

To analyze the frequency of sequential oral squamous cell carcinomas (s-OSCC), preceded by oral potentially malignant disorders, and OSCC de novo (OSCC-dn) and explore differences in their clinicopathologic presentations.

STUDY DESIGN

A structured electronic search strategy identified studies that analyzed frequency, clinical, biological, demographic, biomarkers, and prognostic features of s-OSCC and OSCC-dn according to PRISMA guidelines in PubMed, Scopus, Cochrane Library, and Google Scholar, up to January 31, 2023. Inclusion criteria were original English, Spanish, Portuguese, French, Italian, and German cross-sectional, cohort, and case-control studies. The quality of studies was assessed using the Agency for Research and Health Quality tool and the Newcastle-Ottawa Scale tool.

RESULTS

The final selection included 40 studies. OSCC-dn and s-OSCC represent, respectively, 71% and 29% of cases of OSCC (P = .00), showing a higher percentage of T1 or of T1+T2 in s-OSCC (P < .0001). The association meta-analysis showed OSCC-dn with a significant association. The meta-analysis showed that s-OSCC was significantly associated with smaller tumor size, absence of distant metastases, relapses, male sex, and tumor sites different from tongue; and OSCC-dn was associated with more advanced tumor size, more regional and distant metastases, more advanced stages, and worse survival.

CONCLUSIONS

S-OSCC was less frequent than expected. OSCC-dn seems to have specific clinical, biological, and prognostic features. Future perspectives on oral cancer prevention should address novel approaches and alternatives to screening, such as urgent referral of OSCC-dn.

Immunophenotypic and Gene Expression Analyses of the Inflammatory Microenvironment in High-Grade Oral Epithelial Dysplasia and Oral Lichen Planus

BACKGROUND

Oral lichen planus (OLP) and oral epithelial dysplasia (OED) present diagnostic challenges due to clinical and histologic overlap. This study explores the immune microenvironment in OED, hypothesizing that immune signatures could aid in diagnostic differentiation and predict malignant transformation.

METHODS

Tissue samples from OED and OLP cases were analyzed using immunofluorescence/immunohistochemistry (IF/IHC) for CD4, CD8, CD163/STAT1, and PD-1/PDL-1 expression. RNA-sequencing was performed on the samples, and data was subjected to CIBERSORTx analysis for immune cell composition. Gene Ontology analysis on the immune differentially expressed genes was also conducted.

RESULTS

In OED, CD8 + T-cells infiltrated dysplastic epithelium, correlating with dysplasia severity. CD4 + lymphocytes increased in the basal layer. STAT1/CD163 + macrophages correlated with CD4 + intraepithelial distribution. PD-1/PDL-1 expression varied. IF/IHC analysis revealed differential immune cell composition between OED and OLP. RNA-sequencing identified upregulated genes associated with cytotoxic response and immunosurveillance in OED. Downregulated genes were linked to signaling, immune cell recruitment, and tumor suppression.

CONCLUSIONS

The immune microenvironment distinguishes OED and OLP, suggesting diagnostic potential. Upregulated genes indicate cytotoxic immune response in OED. Downregulation of TRADD, CX3CL1, and ILI24 implies dysregulation in TNFR1 signaling, immune recruitment, and tumor suppression. This study contributes to the foundation for understanding immune interactions in OED and OLP, offering insights into future objective diagnostic avenues.

New insights into the role of the oral leukoplakia microenvironment in malignant transformation

Oral leukoplakia is the most frequent and potentially malignant lesion of the oral cavity. Although dysplasia grading remains the main factor for risk assessment, challenges persist in determining the exact risk of transformation, and the literature has focused on studying alternative biomarkers. The interaction between dysplastic epithelial cells and the microenvironment starts early, and the communication is mainly mediated by lymphocytes, inflammatory factors, fibroblasts, and the extracellular matrix, leading to dysplastic progression. Leukoplakia-infiltrating leukocytes (LILs) and leukoplakia-associated fibroblasts (LAFs) play crucial roles in the dysplastic microenvironment. The immune response is related to intraepithelial T lymphocyte infiltration, mechanisms of immunosuppression coordinated by regulatory T cells, M2 macrophage polarization, and increased numbers of Langerhans cells; in contrast, fibroblastic and extracellular matrix factors are associated with increased numbers of pro-tumorigenic myofibroblasts, increased expression of metalloproteinases vs. decreased expression of TIMPs, and increased expression of chemokines and other inflammatory mediators. The microenvironment offers insights into the progression of leukoplakia to carcinoma, and understanding the complexity of the oral microenvironment in potentially malignant diseases aids in determining the risk of malignant transformation and proposing new therapeutic alternatives.

Predictors of malignant transformation in oral leukoplakia and proliferative verrucous leukoplakia: An observational prospective study including the DNA ploidy status

BACKGROUND

This prospective observational study investigated the determinants of malignant transformation (MT) in localized oral leukoplakia (OL) and proliferative verrucous leukoplakia (PVL).

METHODS

Demographic, clinical, histological, and DNA ploidy status data were collected at enrolment. Survival analysis was performed (MT being the event of interest).

RESULTS

One-hundred and thirty-three patients with OL and 20 patients with PVL entered the study over 6 years (mean follow-up 7.8 years). The presence of OED, DNA ploidy, clinical presentation, and lesion site were associated with MT in patients with OL in a univariate analysis. In a multivariate model, OED was the strongest predictor of MT in patients with OL. Adding DNA ploidy increased the model's predictive power. None of the assessed predictors was associated with MT in patients with PVL.

CONCLUSIONS

DNA ploidy might identify a subset OL with low risk or minimal risk of MT, but it does not seem to be a reliable predictor in patients with PVL.

Total RNA sequencing reveals gene expression and microbial alterations shared by oral pre-malignant lesions and cancer

Head and neck cancers are a complex malignancy comprising multiple anatomical sites, with cancer of the oral cavity ranking among the deadliest and the most disfiguring cancers globally. Oral cancer (OC) constitutes a subset of head and neck cancer cases, presenting primarily as tobacco- and alcohol-associated oral squamous cell carcinoma (OSCC), with a 5-year survival rate of ~ 65%, partly due to the lack of early detection and effective treatments. OSCC arises from premalignant lesions (PMLs) in the oral cavity through a multi-step series of clinical and histopathological stages, including varying degrees of epithelial dysplasia. To gain insights into the molecular mechanisms associated with the progression of PMLs to OSCC, we profiled the whole transcriptome of 66 human PMLs comprising leukoplakia with dysplasia and hyperkeratosis non-reactive (HkNR) pathologies, alongside healthy controls and OSCC. Our data revealed that PMLs were enriched in gene signatures associated with cellular plasticity, such as partial EMT (p-EMT) phenotypes, and with immune response. Integrated analyses of the host transcriptome and microbiome further highlighted a significant association between differential microbial abundance and PML pathway activity, suggesting a contribution of the oral microbiome toward PML evolution to OSCC. Collectively, this study reveals molecular processes associated with PML progression that may help early diagnosis and disease interception at an early stage.

Chemoprevention in oral leukoplakia: challenges and current landscape

Oral potentially malignant disorders have the potential to transform into oral cancer. Oral leukoplakia is a prevalent OPMD with a 9.8% malignant transformation rate. The standard management for OL involves surgical excision, but its efficacy in preventing clinical recurrence and malignant transformation is limited. Therefore, alternative strategies such as chemoprevention modalities have emerged as a promising approach to inhibit the carcinogenesis process. The aim of this review was to identify human studies that investigated the effectiveness of chemopreventive agents in preventing the progression of oral leukoplakia and to provide guidance for future research. Several systemic and topical agents have been evaluated for their potential chemopreventive effects in oral leukoplakia. Systemic agents that have been investigated include vitamin A, lycopene, celecoxib, green tea extract, ZengShengPing, Bowman Birk inhibitor, beta-carotene, curcumin, erlotinib, and metformin. In addition, topical agents tested include bleomycin, isotretinoin, ONYX-015 mouthwash, ketorolac, and dried black raspberry. Despite numerous agents that have already been tested, evidence supporting their effectiveness is limited. To improve the search for an ideal chemopreventive agent for oral leukoplakia, we propose several strategies that can be implemented. Oral leukoplakia chemoprevention presents a promising opportunity for decreasing the incidence of oral cancer. Identifying new chemopreventive agents and biomarkers for predicting treatment response should be a focus of future research.

Reactive and Nonreactive White Lesions of the Oral Mucosa

White lesions in the oral cavity may be diverse in etiology and may present with significant clinical and sometimes histologic overlap between categories, making accurate diagnosis difficult at times. Although white lesions of immune and infectious etiology are covered in another article, this article discusses the differential diagnosis between developmental, reactive, idiopathic, premalignant, and malignant white lesions focusing on clinical features of each category.

Total RNA sequencing reveals gene expression and microbial alterations shared by oral pre-malignant lesions and cancer

Head and neck cancers are a complex malignancy comprising multiple anatomical sites, with cancer of the oral cavity ranking among the deadliest and most disfiguring cancers globally. Oral cancer (OC) constitutes a subset of head and neck cancer cases, presenting primarily as tobacco-and alcohol-associated oral squamous cell carcinoma (OSCC), with a 5-year survival rate of ∼65%, partly due to the lack of early detection and effective treatments. OSCC arises from premalignant lesions (PMLs) in the oral cavity through a multi-step series of clinical and histopathological stages, including varying degrees of epithelial dysplasia. To gain insights into the molecular mechanisms associated with the progression of PMLs to OSCC, we profiled the whole transcriptome of 66 human PMLs comprising leukoplakia with dysplasia and hyperkeratosis non-reactive (HkNR) pathologies, alongside healthy controls and OSCC. Our data revealed that PMLs were enriched in gene signatures associated with cellular plasticity, such as partial EMT (p-EMT) phenotypes, and with immune response. Integrated analyses of the host transcriptome and microbiome further highlighted a significant association between differential microbial abundance and PML pathway activity, suggesting a contribution of the oral microbiome towards PML evolution to OSCC. Collectively, this study reveals molecular processes associated with PML progression that may help early diagnosis and disease interception at an early stage.

AUTHOR SUMMARY

Patients harboring oral premalignant lesions (PMLs) have an increased risk of developing oral squamous cell carcinoma (OSCC), but the underlying mechanisms driving transformation of PMLs to OSCC remain poorly understood. In this study, Khan et al., analyzed a newly generated dataset of gene expression and microbial profiles of oral tissues from patients diagnosed with PMLs from differing histopathological groups, including hyperkeratosis not reactive ( HkNR ) and dysplasia, comparing these profiles with OSCC and normal oral mucosa. Significant similarities between PMLs and OSCC were observed, with PMLs manifesting several cancer hallmarks, including oncogenic and immune pathways. The study also demonstrates associations between the abundance of multiple microbial species and PML groups, suggesting a potential contribution of the oral microbiome to the early stages of OSCC development. The study offers insights into the nature of the molecular, cellular and microbial heterogeneity of oral PMLs and suggests that molecular and clinical refinement of PMLs may provide opportunities for early disease detection and interception.

Characterization of initial/early histologic features of proliferative leukoplakia and correlation with malignant transformation: a multicenter study

The aim of this multicenter retrospective study is to characterize the histopathologic features of initial/early biopsies of proliferative leukoplakia (PL; also known as proliferative verrucous leukoplakia), and to analyze the correlation between histopathologic features and malignant transformation (MT). Patients with a clinical diagnosis of PL who have at least one biopsy and one follow-up visit were included in this study. Initial/early biopsy specimens were reviewed. The biopsies were evaluated for the presence of squamous cell carcinoma (SCCa), oral epithelial dysplasia (OED), and atypical verrucous hyperplasia (AVH). Cases that lacked unequivocal features of dysplasia were termed "hyperkeratosis/parakeratosis not reactive (HkNR)". Pearson chi-square test and Wilcoxon test were used for statistical analysis. There were 86 early/initial biopsies from 59 patients; 74.6% were females. Most of the cases had a smooth/homogenous (34.8%) or fissured appearance (32.6%), and only 13.0% had a verrucous appearance. The most common biopsy site was the gingiva/alveolar mucosa (40.8%) and buccal mucosa (25.0%). The most common histologic diagnosis was OED (53.5%) followed by HkNR (31.4%). Of note, two-thirds of HkNR cases showed only hyperkeratosis and epithelial atrophy. A lymphocytic band was seen in 34.8% of OED cases and 29.6% of HkNR cases, mostly associated with epithelial atrophy. Twenty-eight patients (47.5%) developed carcinoma and 28.9% of early/initial biopsy sites underwent MT. The mortality rate was 11.9%. Our findings show that one-third of cases of PL do not show OED with most exhibiting hyperkeratosis and epithelial atrophy, but MT nevertheless occurred at such sites in 3.7% of cases.

Predicting Progression of Oral Lesions to Malignancy Using Machine Learning

OBJECTIVE

To use large-scale electronic health record (EHR) data to develop machine learning models predicting malignant transformation of oral lesions.

METHODS

A multi-institutional health system database was used to identify a retrospective cohort of patients with biopsied oral lesions. The primary outcome was malignant transformation. Chart review and automated system database queries were used to identify a range of demographic, clinical, and pathologic variables. Machine learning was used to develop predictive models for progression to malignancy.

RESULTS

There were 2192 patients with a biopsied oral lesion, of whom 1232 had biopsy proven oral dysplasia. There was malignant transformation in 34% of patients in the oral lesions dataset, and in 54% of patients in the dysplasia subset. Multiple machine learning-based models were trained on the data in two experiments, (a) including all patients with biopsied oral lesions and (b) including only patients with biopsy-proven dysplasia. In the first experiment, the best machine learning models predicted malignant transformation among the biopsied oral lesions with an area under the curve (AUC) of 86%. In the second experiment, the random forest model predicted malignant transformation among lesions with dysplasia with an AUC of 0.75. The most influential features were dysplasia grade and the presence of multiple lesions, with smaller influences from other features including anemia, histopathologic description of atypia, and other prior cancer history.

CONCLUSION

With diverse features from EHR data, machine learning approaches are feasible and allow for generation of models that predict which oral lesions are likely to progress to malignancy.

LEVEL OF EVIDENCE

3 Laryngoscope, 2022.

Clinical and Histologic Features Associated With Malignant Transformation of Oral Cavity Dysplasia Managed at a Single North American Institution

Importance

Reports characterizing clinical and histologic features associated with a higher risk for development of malignant lesions in the background of an oral potentially malignant disorder have largely reflected East Asian populations. Long-term studies among the North American population are rare.

Objective

To evaluate risk of malignant transformation (MT) of oral dysplastic lesions by investigating the demographic, social, clinical, and histologic factors that may be associated with an increased rate as well as a decreased time to MT.

Design, Setting, and Participants

This was a retrospective cohort study with medical record review at a single institution from January 1, 2000, to December 31, 2019, with follow-up for 20 years. Patients were excluded if they were younger than 18 years, the first biopsy diagnosis showed cancer, biopsies were never performed, biopsies were taken from sites outside of the oral cavity, there was no additional follow-up after the first visit, or the biopsy specimen was not characterized on the spectrum of dysplasia.

Exposures

Diagnosis of leukoplakia of oral mucosa, unspecified lesions of oral mucosa, or other disturbances of oral epithelium.

Main Outcomes and Measures

Main outcome measures included MT rate and time to MT as well as demographic, social, clinical, physical, and histologic features associated with MT.

Results

Thirty-eight of 264 lesions (14%) in 241 patients (132 men and 109 women; mean [SD] age, 64 [13] years) underwent MT. Of the 38 lesions that underwent MT, 19 (50%) underwent transformation by 424 days, 28 (75%) by 870 days, and 34 (90%) by 1600 days. Nodularity, friability, and mass effect were more commonly observed in malignant lesions (nodularity: 42.9% vs 10.0%; difference, 32.9%; OR, 6.72; 95% CI, 3.03-14.89; friability: 42.9% vs 12.8%; difference, 30.1%; OR, 5.11; 95% CI, 1.66-15.69; mass effect: 54.2% vs 10.4%; difference, 43.8%; OR, 10.16; 95% CI, 4.12-25.09). Men were less likely than women to have multiple lesions in the oral cavity (OR, 0.40; 95% CI, 0.22-0.74). Having multiple abnormal sites was associated with higher percentage of MT (OR, 3.38; 95% CI, 1.63-7.01).

Conclusions and Relevance

In this cohort study, nodularity and mass effect were associated with lesions that may push, displace, or invade surrounding tissue, and these were more likely to be present in oral dysplastic lesions that ultimately progressed to cancer. There may be less utility in continuing surveillance beyond 5 years.