Oral Field Cancerization and Its Clinical Implications in the Management in Potentially Malignant Disorders

Manganese suppresses the development of oral leukoplakia by activating the immune response

OBJECTIVE

Manganese ion (Mn2+ ) is reported to promote the antitumor immune response by activating the cGAS-STING pathway, but it is unknown whether Mn2+ can prevent the malignant transformation of precancerous lesions. The effects of Mn2+ in treating oral leukoplakia (OLK) were explored in this work.

METHODS

Peripheral blood Mn analysis of the patients was performed using inductively coupled plasma atomic emission spectroscopy (ICP-AES). A coculture model of dendritic cells (DCs)/macrophages, CD8+ T cells, and dysplastic oral keratinocytes (DOKs) was employed to analyze the role and mechanism of Mn2+ in a simulated OLK immune microenvironment. Western blot, RT-PCR, flow cytometry, enzyme-linked immunosorbent assay (ELISA), and lactate dehydrogenase (LDH) assays were adopted to detect the mechanism of Mn2+ in this model. 4-nitroquinoline oxide (4NQO)-induced OLK mice were used to assess the role of Mn2+ in suppressing OLK progression, and a novel Mn2+ -loaded guanosine-tannic acid hydrogel (G-TA@Mn2+ hydrogel) was fabricated and evaluated for its advantages in OLK therapy.

RESULTS

The content of Mn in patients' peripheral blood was negatively related to the progression of OLK. Mn2+ promoted the maturation and antigen presentation of DCs and macrophages and enhanced the activation of CD8+ T cells in the coculture model, resulting in effective killing of DOKs. Mechanistic analysis found that Mn2+ enhanced the anti-OLK immune response by activating the cGAS-STING pathway. Moreover, Mn2+ suppressed the development of 4NQO-induced carcinogenesis in the mouse model. In addition, the G-TA@Mn2+ hydrogel had better anti-OLK effects.

CONCLUSIONS

Mn2+ enhanced the anti-OLK immune response by activating the cGAS-STING pathway, and the G-TA@Mn2+ hydrogel is a potential novel therapeutic approach for OLK treatment.

The role of podoplanin inhibitors in controlling oral cancer progression

OBJECTIVE

In this article, we review the current studies on the role of podoplanin in oral cancer and the potential application of podoplanin inhibitors as a therapeutic agent for oral cancer.

DESIGN

The narrative review approach was conducted, providing a comprehensive perspective of related literature. Publications addressing podoplanin and its inhibitors in the context of oral cancer were retrieved from PubMed and Scopus databases.

RESULTS

Podoplanin has emerged as a biomarker and therapeutic agent for oral cancer. Numerous studies have reported high podoplanin expression in oral cancer and pre-cancerous lesions compared to normal cells. A specific inhibitor targeting podoplanin may have the potential to prevent oral carcinogenesis via interfering with the pathway of cancerous cells involved in cell proliferation and metastasis. Antibodies, chimeric antigen receptor (CAR)-T cells, cancer-specific mAb (CasMab), synthetic molecules, and lectins are among the materials used as anticancer agents targeting podoplanin. Plant-derived lectins appear to demonstrate a unique advantage against alternative candidates.

CONCLUSIONS

The use of podoplanin inhibitors in place of existing therapeutic approaches could be a promising and novel approach to the prevention and treatment of oral cancer. Nevertheless, further research is required to investigate the practical application of such inhibitors.

The Three-Dimensional In Vitro Cell Culture Models in the Study of Oral Cancer Immune Microenvironment

The onset and progression of oral cancer are accompanied by a dynamic interaction with the host immune system, and the immune cells within the tumor microenvironment play a pivotal role in the development of the tumor. By exploring the cellular immunity of oral cancer, we can gain insight into the contribution of both tumor cells and immune cells to tumorigenesis. This understanding is crucial for developing effective immunotherapeutic strategies to combat oral cancer. Studies of cancer immunology present unique challenges in terms of modeling due to the extraordinary complexity of the immune system. With its multitude of cellular components, each with distinct subtypes and various activation states, the immune system interacts with cancer cells and other components of the tumor, ultimately shaping the course of the disease. Conventional two-dimensional (2D) culture methods fall short of capturing these intricate cellular interactions. Mouse models enable us to learn about tumor biology in complicated and dynamic physiological systems but have limitations as the murine immune system differs significantly from that of humans. In light of these challenges, three-dimensional (3D) culture systems offer an alternative approach to studying cancer immunology and filling the existing gaps in available models. These 3D culture models provide a means to investigate complex cellular interactions that are difficult to replicate in 2D cultures. The direct study of the interaction between immune cells and cancer cells of human origin offers a more relevant and representative platform compared to mouse models, enabling advancements in our understanding of cancer immunology. This review explores commonly used 3D culture models and highlights their significant contributions to expanding our knowledge of cancer immunology. By harnessing the power of 3D culture systems, we can unlock new insights that pave the way for improved strategies in the battle against oral cancer.

The Role of IL-17 in the Pathogenesis of Oral Squamous Cell Carcinoma

Elucidating the inflammatory mechanisms underlying formation and progression of oral squamous cell carcinoma (OSCC) is crucial for discovering new targeted therapeutics. The proinflammatory cytokine IL-17 has proven roles in tumor formation, growth, and metastasis. The presence of IL-17 is demonstrated in both in vitro and in vivo models, and in OSCC patients, is mostly accompanied by enhanced proliferation and invasiveness of cancer cells. Here we review the known facts regarding the role of IL-17 in OSCC pathogenesis, namely the IL-17 mediated production of proinflammatory mediators that mobilize and activate myeloid cells with suppressive and proangiogenic activities and proliferative signals that directly induce proliferation of cancer cells and stem cells. The possibility of a potential IL-17 blockade in OSCC therapy is also discussed.

Understanding the functional relevance of oral neutrophils, phenotype and properties in OSCC

Neutrophils are the predominant white blood cells (WBC) that are recruited to the sites of inflammation and infection. They are acknowledged to perform dual roles by promoting (pro-tumor) or by exhibiting anti-cancer properties (anti-tumor). Neutrophils are characterized based on the changes in phenotype and functional properties. To this context, circulating polymorphonuclear neutrophils (cPMN) and tumor-associated neutrophils (TANs) in cancer biology has been well explored but limited to oral polymorphonuclear neutrophils (oPMNs) in oral squamous cell carcinoma (OSCC). However, oPMNs are eminent in maintaining the healthy oral ecosystem by neutralizing microorganisms. Neutralization process enhances the expression of cell surface markers (CD11b, CD63, CD66, CD66b, CD66c, and CD66e) and inflammatory cytokines (TNF-α, IFN-γ, GM-CSF, and IL-8) and increases the recruitment of neutrophils. Along with the inflammation, it has been reported that CEACAM1 and chemerin also favors the infiltration of neutrophils to the cancer site. This indicates that oPMN might contribute to the aetiology of OSCC. The main objective of this review is to explore, the production and migration of oPMNs to the oral cavity, their phenotypes and possible role in OSCC.

The 'Danse Macabre'-Neutrophils the Interactive Partner Affecting Oral Cancer Outcomes

Over the past few decades, tremendous advances in the prevention, diagnosis, and treatment of cancer have taken place. However for head and neck cancers, including oral cancer, the overall survival rate is below 50% and they remain the seventh most common malignancy worldwide. These cancers are, commonly, aggressive, genetically complex, and difficult to treat and the delay, which often occurs between early recognition of symptoms and diagnosis, and the start of treatment of these cancers, is associated with poor prognosis. Cancer development and progression occurs in concert with alterations in the surrounding stroma, with the immune system being an essential element in this process. Despite neutrophils having major roles in the pathology of many diseases, they were thought to have little impact on cancer development and progression. Recent studies are now challenging this notion and placing neutrophils as central interactive players with other immune and tumor cells in affecting cancer pathology. This review focuses on how neutrophils and their sub-phenotypes, N1, N2, and myeloid-derived suppressor cells, both directly and indirectly affect the anti-tumor and pro-tumor immune responses. Emphasis is placed on what is currently known about the interaction of neutrophils with myeloid innate immune cells (such as dendritic cells and macrophages), innate lymphoid cells, natural killer cells, and fibroblasts to affect the tumor microenvironment and progression of oral cancer. A better understanding of this dialog will allow for improved therapeutics that concurrently target several components of the tumor microenvironment, increasing the possibility of constructive and positive outcomes for oral cancer patients. For this review, PubMed, Web of Science, and Google Scholar were searched for manuscripts using keywords and combinations thereof of "oral cancer, OSCC, neutrophils, TANs, MDSC, immune cells, head and neck cancer, and tumor microenvironment" with a focus on publications from 2018 to 2021.

Mesoscopic fluorescence lifetime imaging: Fundamental principles, clinical applications and future directions

Fluorescence lifetime imaging (FLIm) is an optical spectroscopic imaging technique capable of real-time assessments of tissue properties in clinical settings. Label-free FLIm is sensitive to changes in tissue structure and biochemistry resulting from pathological conditions, thus providing optical contrast to identify and monitor the progression of disease. Technical and methodological advances over the last two decades have enabled the development of FLIm instrumentation for real-time, in situ, mesoscopic imaging compatible with standard clinical workflows. Herein, we review the fundamental working principles of mesoscopic FLIm, discuss the technical characteristics of current clinical FLIm instrumentation, highlight the most commonly used analytical methods to interpret fluorescence lifetime data and discuss the recent applications of FLIm in surgical oncology and cardiovascular diagnostics. Finally, we conclude with an outlook on the future directions of clinical FLIm.

Photodynamic Therapy as an Alternative Therapeutic Tool in Functionally Inoperable Oral and Oropharyngeal Carcinoma: A Single Tertiary Center Retrospective Cohort Analysis

Background: Head and neck cancer is typically treated with surgery, radiotherapy, chemoradiation, or a combination of these treatments. This study aims to retrospectively analyse oncological outcomes, adverse events and toxicity of treatment with temoporfin-mediated photodynamic therapy at a single tertiary referral center. More specifically, in a selected group of patients with otherwise (functionally) inoperable oral or oropharyngeal head and neck squamous cell carcinoma.

Methods: Twenty-six consecutive patients who received photodynamic therapy for oral or oropharyngeal squamous cell carcinoma from January 2002 until July 2019 at the University Hospitals Leuven were included. These were (1) patients with an accessible recurrent or new primary tumor in an extensively treated area of the head and neck, not suitable for standard treatment, or (2) patients that were judged medically unfit to undergo standard treatment modalities.

Results: Complete tumor response immediately after PDT was obtained in 76.9% of cases. During follow-up, a proportion of CR patients did recur, to reach recurrence-free rates at six months, one year and two years of 60.6%, 48.5% and 32.3%. Local control at the PDT treated area was 42.3% with a median recurrence free interval time of 9 months. Recurrence-free interval was statistically more favorable for oropharyngeal squamous cell carcinoma (with or without oral cavity extension) in comparison to oral cavity squamous cell carcinoma alone (p < 0.001). During a median follow-up period of 27 months, we report new tumor activity in 80.8% of patients. Median overall and disease-specific survival time was 31 and 34 months, respectively. Most reported adverse events were pain after treatment and facial edema. At the end of follow-up, swallowing and upper airway functionality were preserved in 76.9 and 95.7% of patients, respectively.

Conclusion: Photodynamic therapy is a valuable treatment option in highly selected patients with oral and/or oropharyngeal (functionally) inoperable head and neck squamous cell carcinoma. Treatment with this alternative modality can induce durable local control in an important fraction of treated patients, with an acceptable toxicity profile.

New Insights into Oral Cancer-Risk Factors and Prevention: A Review of Literature

The oral cancer constitutes 48% of head and neck cancer cases. Ninety percent of oral cancer cases are histologically diagnosed as oral squamous cell carcinomas (OSCCs). Despite new management strategies, the 5-year survival rate of oral cancer is still below 50% in most countries. Head and neck cancers are heterogeneous tumors, and this characteristic of them provides a challenge to treatment plan. Due to the poor outcomes in oral cancer, prevention is a necessity. In this review, a relevant English Literature search in PubMed, ScienceDirect, and Google Scholar from 2000 to mid-2018 was performed. All published articles related to oral cancer and its prevention were included. The risk factors of oral cancer and strategies of oral cancer prevention will be discussed.

Wnt/β-Catenin Signaling in Oral Carcinogenesis

Oral carcinogenesis is a complex and multifactorial process that involves cumulative genetic and molecular alterations, leading to uncontrolled cell proliferation, impaired DNA repair and defective cell death. At the early stages, the onset of potentially malignant lesions in the oral mucosa, or oral dysplasia, is associated with higher rates of malignant progression towards carcinoma in situ and invasive carcinoma. Efforts have been made to get insights about signaling pathways that are deregulated in oral dysplasia, as these could be translated into novel markers and might represent promising therapeutic targets. In this context, recent evidence underscored the relevance of the Wnt/β-catenin signaling pathway in oral dysplasia, as this pathway is progressively "switched on" through the different grades of dysplasia (mild, moderate and severe dysplasia), with the consequent nuclear translocation of β-catenin and expression of target genes associated with the maintenance of representative traits of oral dysplasia, namely cell proliferation and viability. Intriguingly, recent studies provide an unanticipated connection between active β-catenin signaling and deregulated endosome trafficking in oral dysplasia, highlighting the relevance of endocytic components in oral carcinogenesis. This review summarizes evidence about the role of the Wnt/β-catenin signaling pathway and the underlying mechanisms that account for its aberrant activation in oral carcinogenesis.

Rapidly Growing Squamous Cell Carcinoma of the Tongue

The tongue can be a guide for different normal findings/variants, pathological lesions, or signs for systemic diseases. And oral cancer can be among the differentials, which can be detected early by a thorough oral exam. The early detection of oral cancer is particularly important, as the stage of oral cancer at the time of the diagnosis is the most critical factor determining the five-year survival. We present a case of a high-risk patient for oral cancers presented with a rapidly growing tongue lesion over six months that was diagnosed as a squamous cell carcinoma of the tongue on the biopsy. The case highlights an alarming rapid growth nature of oral cancers and alerts the clinicians of the importance of the physical exam as a cost-effective and potentially life-saving measure against oral cancers. It also demonstrates a brief review of risk factors and high-risk features of oral cancers.

Facial cutaneous squamous cell carcinoma - microscopic safety margins and their impact on developing local recurrences

OBJECTIVES

Surgical excision remains the treatment of choice for facial cutaneous squamous cell carcinoma (cSCC) despite there being no generally accepted diameter of clear margins. Therefore, the aim of this study was to evaluate the impact of microscopic clear margins diameter (mCMD) with respect to the development of local recurrences (LR).

MATERIALS AND METHODS

The medical records of 99 patients with a total of 142 cases of facial cSCC, who underwent surgical treatment between January 2010 and December 2015, were reviewed for demographic data and clinicopathological features.

RESULTS

100 cases were diagnosed as primary cSCC and 42 cases as secondary cSCC. Of these, nine (6.3%) developed LR. Mean time to LR was 20 months, with the cheek as the predominant site 55.5% (n = 5). Wound closure was either primary (56%) or secondary (44%), depending on the site. Although no significant correlation between mCMD and LR was found (r_Pearson = 0.029; r_Pearson = 0.015), >4.1 mm was shown to be a negative cut-off-value (horizontally and vertically) without LR (100% vs 0%).

CONCLUSIONS

Based on these results, however descriptive they are, the authors consider histological confirmation of clear margins to be necessary for reducing the formation of LR. Thus, consistent testing and histopathological reporting, in a multicentered effort, are needed to further clarify the role of mCMD in the development of cSCC-LR.

Cancer stem cell markers ALDH1 and Bmi1 expression in oral erythroplakia revisited: Implication for driving the process of field cancerization

The correlation of ALDH1 and Bmi1 expression in potentially malignant oral erythroplakia (OE) with oral carcinoma development was reported in our earlier study. Interestingly, a model of field cancerization orchestrated by the cancer stem cells (CSC) was proposed and suggested the identification of CSC-specific markers is useful for prognosis and providing novel targets for prevention and treatment of field cancerization. We revisited the correlation of ALDH1 and Bmi1 expression in OE with the second and multiple carcinomas development. Strikingly, we observed that the expression of ALDH1 and Bmi1 within a single potentially malignant OE lesion significantly correlate with subsequently developing multiple and multifocal carcinomas, which parallels the process of oral field cancerization. Significantly, ALDH1 and Bmi1 are well-defined markers of CSC for head and neck cancer. Consequently, we provided a preliminary evidence for CSC driving the process of field cancerization.

Podoplanin and ABCG2 expression in oral erythroplakia revisited: Potential evidence for cancer stem cells driving the process of field cancerization

A model of field cancerization orchestrated by the cancer stem cells (CSC) was proposed. Podoplanin and ABCG2 are promising marker of CSCs for head and neck cancer. We revisited the correlation of the two markers with the follow-up data of the patients with oral erythroplakia (OE). Strikingly, we observed that the expression of podoplanin and ABCG2 within a single pre-neoplastic OE lesion significantly correlate with subsequently developing multiple and multifocal carcinomas, thus to some extent demonstrating the concept of field cancerization. Collectively, a point to highlight was that a preliminary evidence that provided by this revisited study supported the perspective on cancer stem cells driving the process of field cancerization.

Intra-operative point-of-procedure delineation of oral cancer margins using optical coherence tomography

OBJECTIVES

Surgical margin status is a significant determinant of treatment outcome in oral cancer. Negative surgical margins can decrease the loco-regional recurrence by five-fold. The current standard of care of intraoperative clinical examination supplemented by histological frozen section, can result in a risk of positive margins from 5 to 17 percent. In this study, we attempted to assess the utility of intraoperative optical coherence tomography (OCT) imaging with automated diagnostic algorithm to improve on the current method of clinical evaluation of surgical margin in oral cancer.

MATERIALS AND METHODS

We have used a modified handheld OCT device with automated algorithm based diagnostic platform for imaging. Intraoperatively, images of 125 sites were captured from multiple zones around the tumor of oral cancer patients (n = 14) and compared with the clinical and pathologic diagnosis.

RESULTS

OCT showed sensitivity and specificity of 100%, equivalent to histological diagnosis (kappa, ĸ = 0.922), in detection of malignancy within tumor and tumor margin areas. In comparison, for dysplastic lesions, OCT-based detection showed a sensitivity of 92.5% and specificity of 68.8% and a moderate concordance with histopathology diagnosis (ĸ = 0.59). Additionally, the OCT scores could significantly differentiate squamous cell carcinoma (SCC) from dysplastic lesions (mild/moderate/severe; p ≤ 0.005) as well as the latter from the non-dysplastic lesions (p ≤ 0.05).

CONCLUSION

The current challenges associated with clinical examination-based margin assessment could be improved with intra-operative OCT imaging. OCT is capable of identifying microscopic tumor at the surgical margins and demonstrated the feasibility of mapping of field cancerization around the tumor.