Is there a relationship between periodontal disease and oral cancer? A systematic review of currently available evidence

The relationship between periodontal disease and cancer: Insights from a Systematic Literature Network Analysis

This paper investigates the relationship between periodontal disease and various cancer types. It provides a comprehensive overview of the existing knowledge about the interaction between periodontal disease and carcinogenesis, explores the underlying biological mechanisms of this connection, and consider the impact of these findings on healthcare practices and future research directions. Utilizing Systematic Literature Network Analysis, which combines bibliometric analysis with Systematic Literature Review, this study analyzes 164 documents from 2000 to 2023. Focus is placed on the 38 most globally cited papers, enabling a targeted and comprehensive analysis of the predominant research within this scope. This review highlights that colorectal, oral, pancreatic, lung, and gastrointestinal cancers have consistent associations with periodontal disease. On the other hand, hematological, breast and prostate cancers show associations with periodontal disease, but these links are less pronounced and more variable, indicating the need for targeted research in these domains. These insights emphasize the necessity for a multidisciplinary healthcare approach, recognizing the systemic implications of periodontal disease.

Oral microbial dysbiosis in patients with oral cavity cancers

OBJECTIVES

The pathogenesis of oral cavity cancers is complex. We tested the hypothesis that oral microbiota dysbiosis is associated with oral cavity cancer.

MATERIALS AND METHODS

Patients with primary oral cavity cancer who met the inclusion and exclusion criteria were included in the study. Matching healthy individuals were recruited as controls. Data on socio-demographic and behavioral factors, self-reported periodontal measures and habits, and current dental status were collected using a structured questionnaire and periodontal chartings. In addition to self-reported oral health measures, each participant received a standard and detailed clinical examination. DNA was extracted from saliva samples from patients and healthy controls. Next-generation sequencing was performed by targeting V3-V4 gene regions of the 16 S rRNA with subsequent bioinformatic analyses.

RESULTS

Patients with oral cavity cancers had a lower quality of oral health than healthy controls. Proteobacteria, Aggregatibacter, Haemophilus, and Neisseria decreased, while Firmicutes, Bacteroidetes, Actinobacteria, Lactobacillus, Gemella, and Fusobacteria increased in oral cancer patients. At the species level, C. durum, L. umeaens, N. subflava, A. massiliensis, and V. dispar were significantly lower, while G. haemolysans was significantly increased (p < 0.05). Major periodontopathogens associated with periodontal disease (P. gingivalis and F.nucleatum) increased 6.5- and 2.8-fold, respectively.

CONCLUSION

These data suggested that patients with oral cancer had worse oral health conditions and a distinct oral microbiome composition that is affected by personal daily habits and may be associated with the pathogenicity of the disease and interspecies interactions.

CLINICAL RELEVANCE

This paper demonstrates the link between oral bacteria and oral cancers, identifying mechanistic interactions between species of oral microbiome.

Periodontitis and the risk of oral cancer: a meta-analysis of case-control studies

OBJECTIVE

The current studies have yielded inconclusive findings regarding the connection between periodontitis  and oral cancer (OC). Therefore, our goal is to elucidate this relationship.

MATERIALS AND METHODS

We conducted a thorough search of electronic databases (EMBASE, PubMed, Web of Science, and Cochrane Library) up to September 2023. The Newcastle-Ottawa Scale (NOS) was applied to assess study quality. To evaluate potential publication bias, both a funnel plot and Egger's test were employed. Additionally, a sensitivity analysis was conducted to explore the source of heterogeneity when the I2 statistic exceeded 50%.

RESULTS

This systematic review encompassed 16 studies, involving a total of 6,032 OC patients and 7,432 healthy controls. Our meta-analysis, incorporating data from nine studies, revealed a significant correlation between periodontitis and the risk of OC (OR [odds ratio] = 2.94, 95% CI [confidence interval] (2.13, 4.07); five studies, 6,927 participants; low certainty of evidence). Findings also suggested that individuals with more than 15 missing teeth may have a heightened risk of OC (OR = 1.91, 95% CI (1.01, 3.62)). Furthermore, clinical attachment loss (CAL) and decayed, missing, and filled teeth (DMFT) in OC patients were more pronounced compared to the control group (CAL, SMD = 1.94, 95% CI (0.22, 3.66); DMFT, SMD = 0.65, 95% CI (0.12, 1.18)).

CONCLUSION

Periodontitis may serve as a potential risk factor for OC. However, caution is warranted in interpreting these findings due to the substantial level of heterogeneity.

Poor Dental Health as a Risk Factor for Alveolar Ridge Malignancies

OBJECTIVE

To determine the association between poor dental health and risk of oral cavity squamous cell cancer (OCSCC) at individual tumor subsites.

STUDY DESIGN

Case-control and cross-sectional METHODS: A case-control study was performed using a population-based cohort in North Carolina (Carolina Head and Neck Cancer Epidemiology Study [CHANCE]). A secondary cross-sectional analysis was performed with an institutional cohort (WashU/Siteman). Cases were adults with primary OCSCC and an identifiable tumor subsite. In the CHANCE cohort, controls were adults without head and neck cancer. In the Washington University/Siteman cohort, patients with tongue cancer served as the comparator group. We used number of missing teeth (categorized 0-6, 7-24, 25-28) as a surrogate for poor dental health, which was self-reported in CHANCE and measured on a pretreatment computed tomography scan in the WashU/Siteman study. Adjusted odds ratios (aORs) for missing teeth were estimated for each tumor subsite using binomial logistic regression models.

RESULTS

Near complete tooth loss (25-28 teeth) was associated with a 3.5-fold increased risk of alveolar ridge malignancy (aOR: 3.51; 95% confidence interval [CI]: 1.14-11.01, P = .03) in the CHANCE study. This association was confirmed in our cross-sectional analysis (WashU/Siteman study) where missing 25-28 teeth was associated with an increased risk of alveolar ridge compared to tongue cancer (aOR: 4.60; 95% CI: 1.97-11.10, P = .001).

CONCLUSIONS

This study suggests an association between poor dental health and risk of alveolar ridge cancer independent of smoking, alcohol use, age, race, and sex. Future prospective and translational studies are needed to confirm this association and elucidate the mechanism of dental disease in alveolar ridge malignancies.

Metabolomics and metagenomics reveal the impact of γδ T inhibition on gut microbiota and metabolism in periodontitis-promoting OSCC

During the process of periodontitis-promoting oral squamous cell carcinoma (OSCC), the periodontitis microbiota can facilitate OSCC development by activating γδ T cells. Inhibiting γδ T cells through immunotherapy has been shown to significantly alleviate various types of cancer. However, the underlying mechanism by which inhibiting γδ T cells influenced cancer treatment has not been fully elucidated. In this study, a mouse model of OSCC with periodontitis was established, and γδ T cells were inhibited by antibodies. Gut samples from the mice were collected and analyzed by metabolomics, metagenomics, and 16S rRNA. Integrative analysis of the gut metabolome and microbiome revealed that targeting γδ T resulted in changes in the levels of metabolites associated with cancer in the gut. Although there was no difference in the α diversity of microbiota, β diversity was significantly different, with a more heterogeneous community structure in the mice receiving targeted γδ T immunotherapy. Statistical analysis of the gut microbiota at the species level revealed a significant enrichment of Lactobacillus murinus, which was significantly correlated with γδ T abundance. The functional analysis revealed that inhibiting γδ T could impact the functional gene. A comprehensive analysis revealed that L. murinus is especially associated with changes in adenine, which also had connection with the concentration of IL-17 and the abundance of γδ T.IMPORTANCEThis study revealed the effect of γδ T cells on gut microbial dysbiosis and identify potential links between gut microbiota and metabolism, providing new insights into the role of γδ T during the process of periodontitis-induced OSCC, and identifying relevant biomarkers for future research and clinical monitoring protocol development.

Role of innate host defense proteins in oral cancerogenesis

It is nowadays well accepted that chronic inflammation plays a pivotal role in tumor initiation and progression. Under this aspect, the oral cavity is predestined to examine this connection because periodontitis is a highly prevalent chronic inflammatory disease and oral squamous cell carcinomas are the most common oral malignant lesions. In this review, we describe how particular molecules of the human innate host defense system may participate as molecular links between these two important chronic noncommunicable diseases (NCDs). Specific focus is directed toward antimicrobial polypeptides, such as the cathelicidin LL-37 and human defensins, as well as S100 proteins and alarmins. We report in which way these peptides and proteins are able to initiate and support oral tumorigenesis, showing direct mechanisms by binding to growth-stimulating cell surface receptors and/or indirect effects, for example, inducing tumor-promoting genes. Finally, bacterial challenges with impact on oral cancerogenesis are briefly addressed.

Periodontal Health and Disease in the Context of Systemic Diseases

During recent years, considerable progress has been made in understanding the etiopathogenesis of periodontitis in its various forms and their interactions with the host. Furthermore, a number of reports have highlighted the importance of oral health and disease in systemic conditions, especially cardiovascular diseases and diabetes. In this regard, research has attempted to explain the role of periodontitis in promoting alteration in distant sites and organs. Recently, DNA sequencing studies have revealed how oral infections can occur in distant sites such as the colon, reproductive tissues, metabolic diseases, and atheromas. The objective of this review is to describe and update the emerging evidence and knowledge regarding the association between periodontitis and systemic disease and to analyse the evidence that has reported periodontitis as a risk factor for the development of various forms of systemic diseases in order to provide a better understanding of the possible shared etiopathogenetic pathways between periodontitis and the different forms of systemic diseases.

Periodontitis and Cancer: Beyond the Boundaries of Oral Cavity

Oral squamous cell carcinoma (OSCC) is the 16th most common cancer and the 15th leading cause of death worldwide, with an incidence of 4 cases per 100,000 people [...]

Network analysis reveals miRNA crosstalk between periodontitis and oral squamous cell carcinoma

BACKGROUND

Oral squamous cell carcinoma (OSCC) is one of the malignant tumors with a poor prognosis. Periodontitis (PD is considered a high-risk factor for OSCC, but the genetic mechanism is rarely studied. This study aims to link OSCC and PD by identifying common differentially expressed miRNAs (Co-DEmiRNAs), their related genes (Hub genes), transcription factors (TFs), signaling pathways, enrichment functions, and compounds, and searching for genetic commonalities.

METHODS

The miRNAs expression datasets of OSCC and PD were searched from the GEO database. The miRNA and related crosstalk mechanism between OSCC and PD was obtained through a series of analyses.

RESULTS

hsa-mir-497, hsa-mir-224, hsa-mir-210, hsa-mir-29c, hsa-mir-486-5p, and hsa-mir-31are the top miRNA nodes in Co-DEmiRNA-Target networks. The most significant candidate miRNA dysregulation genes are ZNF460, FBN1, CDK6, BTG2, and CBX6, while the most important dysregulation TF includes HIF1A, TP53, E2F1, MYCN, and JUN. 5-fluorouracil, Ginsenoside, Rh2, and Formaldehyde are the most correlated compounds. Enrichment analysis revealed cancer-related pathways and so on.

CONCLUSIONS

The comprehensive analysis reveals the interacting genetic and molecular mechanism between OSCC and PD, linking both and providing a foundation for future basic and clinical research.

Metaproteomic Analysis of an Oral Squamous Cell Carcinoma Dataset Suggests Diagnostic Potential of the Mycobiome

Oral squamous cell carcinoma (OSCC) is the most common head and neck malignancy, with an estimated 5-year survival rate of only 40-50%, largely due to late detection and diagnosis. Emerging evidence suggests that the human microbiome may be implicated in OSCC, with oral microbiome studies putatively identifying relevant bacterial species. As the impact of other microbial organisms, such as fungi and viruses, has largely been neglected, a bioinformatic approach utilizing the Trans-Proteomic Pipeline (TPP) and the R statistical programming language was implemented here to investigate not only bacteria, but also viruses and fungi in the context of a publicly available, OSCC, mass spectrometry (MS) dataset. Overall viral, bacterial, and fungal composition was inferred in control and OSCC patient tissue from protein data, with a range of proteins observed to be differentially enriched between healthy and OSCC conditions, of which the fungal protein profile presented as the best potential discriminator of OSCC within the analysed dataset. While the current project sheds new light on the fungal and viral spheres of the oral microbiome in cancer in silico, further research will be required to validate these findings in an experimental setting.

Influence of site and smoking on malignant transformation in the oral cavity: Is the microbiome the missing link?

The tongue and floor of the mouth are high-risk sites for oral squamous cell carcinoma (OSCC), while smoking is its most significant risk factor. Recently, questions have been raised as to the role of the oral microbiome in OSCC because of a wealth of evidence demonstrating that the microbiome of OSCC differs from that of healthy mucosa. However, oral site and smoking also have a significant impact on oral microbial communities, and to date, the role these factors play in influencing the dysbiotic microbial communities of OSCC and precursor lesions has not been considered. This review aims to examine the influence of site and smoking on the oral microbiome and, in turn, whether these microbiome changes could be involved in oral carcinogenesis.

Periodontal disease is associated with the risk of cardiovascular disease independent of sex: A meta-analysis

Objectives

Studies have established a link between periodontal disease and cardiovascular disease (CVD), but it is unclear whether there is a sex difference in their association.

Methods

The PubMed, Embase, and Cochrane databases were searched until June, 21 2022. Cardiovascular outcomes included any CVD, myocardial infarction (MI), coronary heart disease (CHD), or stroke. Studies reported the prevalence of CVD in patients with periodontal disease and the relationship between periodontal disease and CVD. The study is registered with PROSPERO (CRD42022333663). The level of evidence and recommendations is assessed by the Grading of Recommendations for Assessment, Development and Evaluation (GRADE).

Results

Twenty-six studies were included. In patients with periodontal disease, the prevalence of CVD was 7.2% [9 studies; 95% confidence interval (CI): 2.7-13.6%], and prevalence for CHD, hypertension, stroke, and heart failure was 6.6, 25.3, 1, and 1.1%, respectively. There was a significant association between periodontal disease and CVD in men [odds ratio (OR) = 1.22; 95% CI: 1.12-1.34] and women (OR = 1.11; 95% CI: 1.05-1.17), with no significant sex difference (P > 0.05).

Conclusion

Cardiovascular disease is relatively common in patients with periodontal disease, and an increased risk of CVD is associated with periodontal disease independent of sex. Interventions targeting periodontal disease may be beneficial for CVD.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022333663.

Dental Care for Older Adults

There is a global increase in the older population. Unfortunately, dental conditions in the older population can sometimes be poor as a result of worsened physical conditions and the cumulative damage caused by dental diseases in the past. Many suffer from oral diseases such as dental caries and periodontal disease but receive no regular dental care. Oral conditions and systemic problems are interrelated. Chronic medical problems and polypharmacy are common among them. These conditions may lead to xerostomia with or without a decrease in saliva output. Additionally, many older adults have deteriorated masticatory function associated with physical health issues such as frailty. Preventive measures are crucial to stop oral diseases from progressing and the replacement of missing teeth is needed when masticatory function is impaired. Older adults also suffer a higher risk of oral cancer because of their less resilient but more permeable oral mucosa. With the increasing need for elderly dental care, dentists should equip themselves with knowledge and skills in geriatric dentistry. They should help older adults to develop and maintain the functional ability that enables well-being in older age. This communication article aims to discuss the relevant medical conditions, common dental diseases, and dental care for older adults.

Periodontal Pathogens: A Crucial Link Between Periodontal Diseases and Oral Cancer

Emerging evidence shows a striking link between periodontal diseases and various human cancers including oral cancer. And periodontal pathogens, leading to periodontal diseases development, may serve a crucial role in oral cancer. This review elucidated the molecular mechanisms of periodontal pathogens in oral cancer. The pathogens directly engage in their own unique molecular dialogue with the host epithelium to acquire cancer phenotypes, and indirectly induce a proinflammatory environment and carcinogenic substance in favor of cancer development. And functional, rather than compositional, properties of oral microbial community correlated with cancer development are discussed. The effect of periodontal pathogens on periodontal diseases and oral cancer will further detail the pathogenesis of oral cancer and intensify the need of maintaining oral hygiene for the prevention of oral diseases including oral cancer.

Is periodontal disease a risk factor for oral cancer?

Aim This study aimed to investigate periodontal disease as a non-genetic risk factor for oral cancer.Design Case-control study.Patient population Two hundred patients, regardless of periodontal and adverse habits (smoking and alcohol) status, in the age group of 18-90 years were included in this institutional study. One hundred patients with histologically confirmed oral squamous cell carcinoma (OSCC) were included in the case group, while the control group had 100 patients without any oral cancer.Methods Multivariable examination to obtain socioeconomic and lifestyle risk factors was performed with a questionnaire for both the groups and compared statistically. Additionally, oral status (periodontal stage, clinical attachment loss, periodontal pocket depth, bleeding on probing, Silness-Loe plaque index, and decayed, missing, and filled teeth [DMFT] index) of both the groups was recorded and compared statistically.Results A significant correlation was found between age, gender and development of oral cancer. There was a significant co-relation between alcohol intake and oral cancer development. Surprisingly, there was no correlation between smoking habits and passive smoking with oral cancer development in the case group. Overall, 72.1% of case group patients had Stage 4 periodontitis, whereas 51.6% of control group patients had Stage 2 periodontitis. A significant correlation was found between the incidence of oral cancer and the stage of periodontitis.Conclusion The findings of the study support the hypothesis that periodontitis is an independent risk factor for oral cancer.

Microbial and molecular differences according to the location of head and neck cancers

Background

Microbiome has been shown to substantially contribute to some cancers. However, the diagnostic implications of microbiome in head and neck squamous cell carcinoma (HNSCC) remain unknown.

Methods

To identify the molecular difference in the microbiome of oral and non-oral HNSCC, primary data was downloaded from the Kraken-TCGA dataset. The molecular differences in the microbiome of oral and non-oral HNSCC were identified using the linear discriminant analysis effect size method.

Results

In the study, the common microbiomes in oral and non-oral cancers were Fusobacterium, Leptotrichia, Selenomonas and Treponema and Clostridium and Pseudoalteromonas, respectively. We found unique microbial signatures that positively correlated with Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways in oral cancer and positively and negatively correlated KEGG pathways in non-oral cancer. In oral cancer, positively correlated genes were mostly found in prion diseases, Alzheimer disease, Parkinson disease, Salmonella infection, and Pathogenic Escherichia coli infection. In non-oral cancer, positively correlated genes showed Herpes simplex virus 1 infection and Spliceosome and negatively correlated genes showed results from PI3K-Akt signaling pathway, Focal adhesion, Regulation of actin cytoskeleton, ECM-receptor interaction and Dilated cardiomyopathy.

Conclusions

These results could help in understanding the underlying biological mechanisms of the microbiome of oral and non-oral HNSCC. Microbiome-based oncology diagnostic tool warrants further exploration.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-022-02554-6.

Leaky Gum: The Revisited Origin of Systemic Diseases

The oral cavity is the gateway for microorganisms into your body where they disseminate not only to the directly connected respiratory and digestive tracts but also to the many remote organs. Oral microbiota, travelling to the end of the intestine and circulating in our bodies through blood vessels, not only affect a gut microbiome profile but also lead to many systemic diseases. By gathering information accumulated from the era of focal infection theory to the age of revolution in microbiome research, we propose a pivotal role of “leaky gum”, as an analogy of “leaky gut”, to underscore the importance of the oral cavity in systemic health. The oral cavity has unique structures, the gingival sulcus (GS) and the junctional epithelium (JE) below the GS, which are rarely found anywhere else in our body. The JE is attached to the tooth enamel and cementum by hemidesmosome (HD), which is structurally weaker than desmosome and is, thus, vulnerable to microbial infiltration. In the GS, microbial biofilms can build up for life, unlike the biofilms on the skin and intestinal mucosa that fall off by the natural process. Thus, we emphasize that the GS and the JE are the weakest leaky point for microbes to invade the human body, making the leaky gum just as important as, or even more important than, the leaky gut.

Molecular Mechanisms Leading from Periodontal Disease to Cancer

Periodontitis is prevalent in half of the adult population and raises critical health concerns as it has been recently associated with an increased risk of cancer. While information about the topic remains somewhat scarce, a deeper understanding of the underlying mechanistic pathways promoting neoplasia in periodontitis patients is of fundamental importance. This manuscript presents the literature as well as a panel of tables and figures on the molecular mechanisms of Porphyromonas gingivalis and Fusobacterium nucleatum, two main oral pathogens in periodontitis pathology, involved in instigating tumorigenesis. We also present evidence for potential links between the RANKL–RANK signaling axis as well as circulating cytokines/leukocytes and carcinogenesis. Due to the nonconclusive data associating periodontitis and cancer reported in the case and cohort studies, we examine clinical trials relevant to the topic and summarize their outcome.

Alterations of the Oral Microbiota Profiles in Chinese Patient With Oral Cancer

Oral cancer is the most common malignant tumor in the oral and maxillofacial region, of which more than 90% is squamous cell carcinoma. The incidence of oral cancer is on the rise worldwide. An imbalance between the microorganism composition and its host may lead to the occurrence of oral malignant tumors. Accumulating evidence suggests that the oral microbiota plays an important role in oral cancer; however, the association between oral microbiota and oral cancer has not yet been comprehensively studied. In this study, metagenomic sequencing was used to compare the microbial composition of three groups of samples from Chinese patients with oral cancer, patients with precancerous lesion, and normal individuals. In terms of microbiota richness, the oral microbiota of patients with precancerous lesions was richer than that of oral cancer patients and healthy controls, whereas in terms of microbiota diversity, there was little difference between the three groups. The three groups of samples exhibited statistically significant differences in microbiota composition and metabolic function at the family, genus, and species levels (P < 0.05). The differentially enriched phylum in oral cancer samples was Bacteroidetes (P < 0.05). At the genus level, the main differentially enriched taxa were Prevotella, Peptostreptococcus, Carnobacterium, and Diastella (P < 0.05). The species level was differentially enriched in Prevotella intermedia and Peptostreptococcus stomatis (p < 0.05). The prediction of microbiota function shows that oral cancer is mainly associated with coenzyme A biosynthesis, phosphopantothenic acid biosynthesis, inosine 5’-phosphate degradation, and riboflavin biosynthesis. Furthermore, the increase in C-reactive protein level in oral cancer patients was found to be closely related to P. intermedia. Overall, oral bacterial profiles showed significant differences between the oral cancer group and normal group. Hence, microbes can be employed as diagnostic markers and treatment targets for oral cancer.

Periodontitis as a risk for oral cancer: a case-control study

Background

The aetiology of oral cancer is multifactorial, as various risk factors (genetics, socioeconomic and lifestyle factors) contribute to its development. Data in the literature suggest that people with periodontal disease have an increased risk of developing oral cancer, and the severity of periodontitis correlates with the appearance of oral squamous cell carcinoma. The aim of this study was to revise the non-genetic risk factors that may influence the development of OC, while focusing on the dental and periodontal status and OH.

Methods

Two hundred patients (hundred diagnosed with oral cancer and hundred without oral cancer) were enrolled in our case–control study, to evaluate the association between oral cancer and the presence and severity of periodontitis, while examining several risk factors that might be responsible for oral cancer formation. A questionnaire customised for oral cancer patients was used to obtain the socioeconomic and lifestyle risk factors that may influence the development of oral squamous cell carcinoma. The dental and periodontal status along with the level of oral hygiene was recorded quantitatively. The chi-square and Mann–Whitney tests and logistic regression were used for the statistical analysis.

Results

By considering both the case and the control groups, a significant correlation was found between the incidence of oral cancer and some socioeconomic factors and lifestyle habits, such as the sex, age, education and alcohol consumption of an individual. The mean value of the Silness-Löe plaque index was significantly higher in the case population. The number of completely edentulous patients was higher among the oral cancer population. The incidence of oral cancer was 57.1% in patients with periodontal disease. In comparison, the incidence of oral squamous cell carcinoma was only 28.6% among the patients without periodontitis. Most of the oral cancer patients (72.1%) had stage 4 periodontitis. On the other hand, the vast majority of the control group (51.6%) had stage 2 periodontitis.

Conclusion

Periodontitis can be an individual risk factor for oral cancer development. Periodontally compromised individuals should be strictly monitored, especially those with severe periodontitis and coexisting lifestyle risk factors. Maintaining their periodontal health in at-risk patients can minimize cancer risks.

A Case of Mandibular Cancer Involving Almost Entire Attached Gingiva

Here we describe a rare case of mandibular cancer involving almost the entire attached gingiva in a 71-year-old man. First, marginal resection of the entire mandible was performed, followed by one-stage reconstruction comprising application of a split-thickness skin graft onto the wound. This resulted in good alveolar ridge morphology, allowing for a mandibular prosthesis to be installed soon postoperatively. Histopathological analysis revealed a well-differentiated squamous cell carcinoma extending throughout most of the resected attached gingiva, but no malignant features in the stumps. Furthermore, no infiltration into the jawbone was observed, and no vascular or lymphatic invasion or perineural infiltration. At 3 years postoperatively, the patient's clinical course has remained uneventful, with no recurrence or problems arising in the remaining mandible. The patient is also able to eat regularly using the mandibular prosthesis provided.

The Role of Periodontopathogens and Oral Microbiome in the Progression of Oral Cancer. A Review

Chronic periodontal disease and oral bacteria dysbiosis can lead to the accumulation of genetic mutations that eventually stimulate Oral Squamous Cell Cancer (OSCC). The annual incidence of OSCC is increasing significantly, and almost half of the cases are diagnosed in an advanced stage. Worldwide there are more than 380,000 new cases diagnosed every year, and a topic of extensive research in the last few years is the alteration of oral bacteria, their compositional changes and microbiome. This review aims to establish the relationship between bacterial dysbiosis and OSCC. Several bacteria implicated in periodontal disease, including Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, and some Streptococcus species, promote angiogenesis, cell proliferation, and alteration in the host defense process; these same bacteria have been present in different stages of OSCC. Our review showed that genes involved in bacterial chemotaxis, the lipopolysaccharide (LPS) of the cell wall membrane of gram negatives bacteria, were significantly increased in patients with OSCC. Additionally, some bacterial diversity, particularly with Firmicutes, and Actinobacteria species, has been identified in pre-cancerous stage samples. This review suggests the importance of an early diagnosis and more comprehensive periodontal therapy for patients by the dental care professional.

Association between periodontal disease and oral cancer screening among US adults: NHANES 2011-2014

OBJECTIVES

To examine oral cancer screening rates and associated factors among adults with periodontal disease (PD). We hypothesized that adults with severe PD will be less likely to report receipt of any type of oral cancer screening than adults with no PD.

MATERIALS AND METHODS

We used 2011-2014 National Health and Nutrition Examination Survey (NHANES) data on adults ≥30 years. PD status was classified as no PD, mild/moderate PD and severe PD. Survey-adjusted logistic regression analysis was used to examine the model adjusted risk ratio (RR) and 95% confidence intervals (CI) for the outcome of not receiving intraoral, extraoral or both types of oral cancer screenings among adults with PD. Control variables included age, sex, race/ethnicity, health insurance, education, income level, smoking status, alcohol use and last dental visit.

RESULTS

The analytic sample included 6962 adults weighted to the national population of adults who had a periodontal examination during 2011-2014. Overall, 31.5%, 26.8% and 20.9% of adults reported receipt of intraoral, extraoral and both types of oral cancer screening, respectively. Almost 40% of adults had some form of PD (7.6% severe and 32.4% mild/moderate PD). A higher proportion of 45-64-year-olds, males, non-Hispanic Blacks, those with less than high school education, with income level less than 200% federal poverty level, or those with no insurance had severe PD than no PD. In adjusted analyses, adults with severe PD were significantly more likely to report no receipt of intraoral (RR = 1.25, 95% CI = 1.12-1.40), extraoral (RR = 1.17, 95% CI = 1.07-1.27) or both types of oral cancer screenings (RR = 1.18, 95% CI = 1.10-1.27) than those with no PD.

CONCLUSIONS

Significantly low proportion of adult's age ≥30 years with severe PD reported receiving any type of oral cancer screening. The association between PD and risk of oral cancers points to the need to improve oral cancer screening rates among adults with PD.

Smoking and Drinking Adjusted Association between Head and Neck Cancers and Oral Health Status Related to Periodontitis: a Meta-Analysis

BACKGROUND

Not so many reports about the association between head and neck cancer (HNC) and oral health status related to periodontitis (OHS-P) has been published in different countries with different methods. So, there is a need for an extensive meta-analysis with the total articles published until 2020. Hence, this study aimed to estimate the association between HNC and OHS-P through a meta-analysis.

METHODS

Based on Preferred Reporting Items for Systematic Reviews and Meta Analyses guidelines, 22 studies were selected through PubMed and Cochrane Library databases. Meta-analysis using them was performed to evaluate the association. The risk of bias assessment using the Newcastle-Ottawa Scale (NOS) was applied to evaluate the quality of non-randomized studies. Publication bias was evaluated by funnel plot and Egger's regression test.

RESULTS

Since heterogeneity was significant (I² = 88%, P < 0.001), we adopted the random effect model for 22 studies. Those with bad OHS-P, compared to those with good OHS-P, were more likely to have the risk of HNC by 2.4 times (odds ratio [OR], 2.42; 95% confidence interval [CI], 1.88-3.13) for random effect model. The association included publication bias (Egger's regression, P value < 0.001). The association among five studies (I² = 39%, P = 0.16) using alveolar bone loss (ABL) or clinical attachment level (CAL) for assessing periodontitis increased to OR of 3.85 (CI, 3.04-4.88) in the fixed effect model without publication bias (Egger's regression, P = 0.66). Moreover, the association was higher in 10 fair or good NOS studies (OR, 3.08) and in 7 Asian studies (OR, 2.68), which were from the fixed model without publication bias.

CONCLUSION

Our meta-analysis showed that bad OHS-P was associated with the risk of HNC. The association was stronger in studies using ABL or CAL for assessing periodontitis.

Meta-omics analysis indicates the saliva microbiome and its proteins associated with the prognosis of oral cancer patients

Saliva is a biofluid that maintains the health of oral tissues and the homeostasis of oral microbiota. Studies have demonstrated that Oral squamous cell carcinoma (OSCC) patients have different salivary microbiota than healthy individuals. However, the relationship between these microbial differences and clinicopathological outcomes is still far from conclusive. Herein, we investigate the capability of using metagenomic and metaproteomic saliva profiles to distinguish between Control (C), OSCC without active lesion (L0), and OSCC with active lesion (L1) patients. The results show that there are significantly distinct taxonomies and functional changes in L1 patients compared to C and L0 patients, suggesting compositional modulation of the oral microbiome, as the relative abundances of Centipeda, Veillonella, and Gemella suggested by metagenomics are correlated with tumor size, clinical stage, and active lesion. Metagenomics results also demonstrated that poor overall patient survival is associated with a higher relative abundance of Stenophotromonas, Staphylococcus, Centipeda, Selenomonas, Alloscordovia, and Acitenobacter. Finally, compositional and functional differences in the saliva content by metaproteomics analysis can distinguish healthy individuals from OSCC patients. In summary, our study suggests that oral microbiota and their protein abundance have potential diagnosis and prognosis value for oral cancer patients. Further studies are necessary to understand the role of uniquely detected metaproteins in the microbiota of healthy and OSCC patients as well as the crosstalk between saliva host proteins and the oral microbiome present in OSCC.

Association of periodontitis and tooth loss with liver cancer: A systematic review

A number of epidemiological studies have suggested a positive association between periodontal diseases and oro-digestive cancers, including liver cancer. The purpose of the present systematic review was to analyze the current evidence regarding the potential association between periodontitis and/or tooth loss and the risk of liver cancer. A comprehensive search of PubMed, Scopus and Web of Science databases was conducted in August 2019. The inclusion criteria comprised all observational studies that assessed the relationship between periodontitis or tooth loss and liver cancer. Case reports, animal studies, experimental studies, and reviews were excluded. Due to great heterogeneity among the included studies, no meta-analysis was conducted. Six studies (five prospective cohorts and one case-control) comprising 619,834 subjects (including 916 liver cancer cases) were included. The studies were conducted in the United States, Europe, and Asia. Three large-scale cohort studies reported a positive association between periodontitis or tooth loss and the risk of liver cancer. One case-control study found some association between liver cancer and loss of 12-23 teeth, but such association was not replicated in patients with greater number of tooth loss. Contrarily, two studies failed to report any association between periodontitis and/or tooth loss and the risk of liver cancer. The available evidence suggests a possible link between tooth loss/periodontitis and the risk of liver cancer. However, the evidence is not conclusive enough, a fact that drives to conduct more, well-designed, prospective cohort studies to further explore the potential association between periodontitis and the risk of liver cancer.

Effect of Periodontitis and Scaling and Root Planing on Risk of Pharyngeal Cancer: A Nested Case-Control Study

This study investigated the association between periodontitis and the risk of pharyngeal cancer in Taiwan. For this population-based nested case–control study using the Longitudinal Health Insurance Database derived from Taiwan’s National Health Insurance Research Database, we identified patients (n = 1292) who were newly diagnosed with pharyngeal cancer between 2005 and 2013 and exactly paired them with propensity score matched control subjects (n = 2584). Periodontitis and scaling and root planing (SRP) were identified before the index date. Pharyngeal cancer was subdivided into 3 subgroups on the basis of anatomic location: nasopharyngeal cancer, oropharyngeal cancer, and hypopharyngeal cancer. A multiple conditional logistic regression model was applied to analyze the adjusted odds ratio (aOR). Periodontitis was associated with an increased risk of pharyngeal cancer (aOR, 1.57; 95% confidence interval (CI), 1.17 to 2.10), especially oropharyngeal cancer (aOR, 2.22; 95% CI, 1.07 to 4.60). We found a decreased risk of pharyngeal cancer in patients who had undergone SRP (aOR, 0.77; 95% CI, 0.61 to 0.96). In conclusion, this study showed that periodontitis was associated with an increased risk of pharyngeal cancer and SRP exerted a protective effect against pharyngeal cancer. Our results suggest that treating periodontitis and performing SRP, which are modifiable factors in oral health, in clinical practice may provide an opportunity to decrease the disease burden of pharyngeal cancer in Taiwan.

Innate immune mechanisms to oral pathogens in oral mucosa of HIV-infected individuals

A crucial aspect of mucosal HIV transmission is the interaction between HIV, the local environmental milieu and immune cells. The oral mucosa comprises many host cell types including epithelial cells, CD4 + T cells, dendritic cells and monocytes/macrophages, as well as a diverse microbiome predominantly comprising bacterial species. While the oral epithelium is one of the first sites exposed to HIV through oral-genital contact and nursing infants, it is largely thought to be resistant to HIV transmission via mechanisms that are still unclear. HIV-1 infection is also associated with predisposition to secondary infections, such as tuberculosis, and other diseases including cancer. This review addresses the following questions that were discussed at the 8th World Workshop on Oral Health and Disease in AIDS held in Bali, Indonesia, 13 September –15 September 2019: (a) How does HIV infection affect epithelial cell signalling? (b) How does HIV infection affect the production of cytokines and other innate antimicrobial factors, (c) How is the mucosal distribution and function of immune cells altered in HIV infection? (d) How do T cells affect HIV (oral) pathogenesis and cancer? (e) How does HIV infection lead to susceptibility to TB infections?

The Role of the Microbiome in Oral Squamous Cell Carcinoma with Insight into the Microbiome-Treatment Axis

Oral squamous cell carcinoma (OSCC) is one of the leading presentations of head and neck cancer (HNC). The first part of this review will describe the highlights of the oral microbiome in health and normal development while demonstrating how both the oral and gut microbiome can map OSCC development, progression, treatment and the potential side effects associated with its management. We then scope the dynamics of the various microorganisms of the oral cavity, including bacteria, mycoplasma, fungi, archaea and viruses, and describe the characteristic roles they may play in OSCC development. We also highlight how the human immunodeficiency viruses (HIV) may impinge on the host microbiome and increase the burden of oral premalignant lesions and OSCC in patients with HIV. Finally, we summarise current insights into the microbiome–treatment axis pertaining to OSCC, and show how the microbiome is affected by radiotherapy, chemotherapy, immunotherapy and also how these therapies are affected by the state of the microbiome, potentially determining the success or failure of some of these treatments.

The Oral Microbiome and Cancer

There is mounting evidence that members of the human microbiome are highly associated with a wide variety of cancer types. Among oral cancers, oral squamous cell carcinoma (OSCC) is the most prevalent and most commonly studied, and it is the most common malignancy of the head and neck worldwide. However, there is a void regarding the role that the oral microbiome may play in OSCC. Previous studies have not consistently found a characteristic oral microbiome composition associated with OSCC. Although a direct causality has not been proven, individual members of the oral microbiome are capable of promoting various tumorigenic functions related to cancer development. Two prominent oral pathogens, Porphyromonas gingivalis, and Fusobacterium nucleatum can promote tumor progression in mice. P. gingivalis infection has been associated with oro-digestive cancer, increased oral cancer invasion, and proliferation of oral cancer stem cells. The microbiome can influence the evolution of the disease by directly interacting with the human body and significantly altering the response and toxicity to various forms of cancer therapy. Recent studies have shown an association of certain phylogenetic groups with the immunotherapy treatment outcomes of certain tumors. On the other side of the coin, recently it has been a resurgence in interest on the potential use of bacteria to cure cancer. These kinds of treatments were used in the late nineteenth and early twentieth centuries as the first line of defense against cancer in some hospitals but later displaced by other types of treatments such as radiotherapy. Currently, organisms such as Salmonella typhimurium and Clostridium spp. have been used for targeted strategies as potential vectors to treat cancer. In this review, we briefly summarize our current knowledge of the role of the oral microbiome, focusing on its bacterial fraction, in cancer in general and in OSCC more precisely, and a brief description of the potential use of bacteria to target tumors.

Possible association of periodontal disease with oral cancer and oral potentially malignant disorders: a systematic review

Background: Periodontitis has been associated with several systemic diseases and medical conditions, including oral cancer (OC). However, most studies reporting an association between OC and periodontal disease have used different clinical and radiographic criteria to define periodontal disease. This review aimed to evaluate the currently available evidence to determine an association between periodontal disease (extension and severity), OC, and oral potentially malignant disorders (OPMDs).Material and methods: A systematic search of studies published up to August 2018 was performed following the PRISMA guidelines in the electronic databases MEDLINE (PubMed) and COCHRANE (OVID). A methodological evaluation was made using the Strengthening the Reporting of Observational studies in Epidemiology (STROBE) checklist.Results: Eight studies (case-control, cross-sectional and cohort) were included. An increased clinical attachment loss, plaque index, bleeding on probing, and radiographic bone loss was found in patients with OC and OPMDs. Differences in the methodological characteristics, case definition used for periodontal diseases, and OC location did not allow estimating the odds ratio required to conduct a meta-analysis.Conclusion: Some studies suggest a positive relationship between periodontal disease, OC, and OPMDs; however, the currently available evidence is insufficient to draw solid conclusions.

Metabolic landscape of oral squamous cell carcinoma

BACKGROUND

Head and neck cancers are the seventh most common type of cancer worldwide, with almost half of the cases affecting the oral cavity. Oral squamous cell carcinoma (OSCC) is the most common form of oral cancer, showing poor prognosis and high mortality. OSCC molecular pathogenesis is complex, resulting from a wide range of events that involve the interplay between genetic mutations and altered levels of transcripts, proteins, and metabolites. Metabolomics is a recently developed sub-area of omics sciences focused on the comprehensive analysis of small molecules involved in several biological pathways by high throughput technologies.

AIM OF REVIEW

This review summarizes and evaluates studies focused on the metabolomics analysis of OSCC and oral premalignant disorders to better interpret the complex process of oral carcinogenesis. Additionally, the metabolic biomarkers signatures identified so far are also included. Moreover, we discuss the limitations of these studies and make suggestions for future investigations.

KEY SCIENTIFIC CONCEPTS

Although many questions about the metabolic features of OSCC have already been answered in metabolomic studies, further validation and optimization are still required to translate these findings into clinical applications.

Oral Potentially Malignant Disorders and Oral Cavity Cancer

The Surveillance, Epidemiology, and End Results program from the National Cancer Institute reports that the aggregate number of oral cavity and pharyngeal cancer cases has been increasing over the past decade and, despite an overall decline in oral cavity cancers, this increase is largely related to a dramatic increase in cancers involving oropharyngeal subsites. Early detection of oral cavity cancers is commensurate with improved survival, and opportunistic screening by trained clinicians to detect oral cavity cancer and oral potentially malignant disorders is recommended by the American Dental Association and the American Academy of Oral Medicine.

Periodontal disease and cancer: Epidemiologic studies and possible mechanisms

Epidemiologic and cancer control studies on the association of periodontal disease and cancer risk mostly suggest a positive association with overall cancer risk and certain specific types of cancer. These findings are generally consistent among cross‐sectional and longitudinal studies. In this paper, we review epidemiologic studies and current knowledge on periodontal disease and cancer, with a focus on those studies conducted in the years following the Joint European Federation of Periodontology/American Academy of Periodontology Workshop on “Periodontitis and Systemic Diseases” in November 2012. This review also explores the role of chronic inflammation as a biologically plausible mechanistic link between periodontal disease and risk of cancer. Furthermore, it highlights studies that have examined the potential importance of certain periodontal pathogens in this association.

Periodontal Diseases as Putative Risk Factors for Head and Neck Cancer: Systematic Review and Meta-Analysis

Whether "periodontal disease" can be considered as an independent risk factor for head and neck cancer (HNC) remains controversial. The aim of the current meta-analysis was to quantitatively assess this relationship in order to determine whether this represents a true risk factor, with implications for cancer prevention and management. PubMed, Scopus, and Embase databases were systematically searched. Selective studies were reviewed, and meta-analysis was performed to estimate the pooled odds ratio (OR) with 95% confidence intervals (CIs) on eligible studies using a random effects model. In total, 21 eligible observational studies (4 cohorts and 17 case-controls) were identified for qualitative synthesis after a review of 1051 articles. Significant heterogeneity could be identified in measures utilized for reporting of periodontal disease. Meta-analysis performed on nine studies that employed objective measures for reporting periodontal disease demonstrated a significant association between periodontal disease and HNC [OR 3.17, 95% CI, 1.78-5.64]. A diseased periodontium represents an independent risk marker, and a putative risk factor, for HNC. Prospective studies with standardized measures of periodontal disease severity and extent, integrated with microbiological and host susceptibility facets, are needed to elucidate the mechanisms of this positive association and whether treatment of the former influences the incidence and outcomes for HNC.

Risk factors of head and neck cancer mortality compared with those of all-cause and all-cancer mortalities

This study aimed to clarify the risk factors of head and neck cancer (HNC) mortality, relative to those of all-cause and all-cancer mortalities, using the Korean National Health Insurance Service-Health Screening Cohort (NHIS-HEALS) data set. Data from 238 HNC deaths, 14,769 all-cancer deaths, and 38,086 all-cause deaths were extracted during a median follow-up period of 9.5 years. Baseline characteristics were assessed via chi-square tests, t tests, and multivariable logistic regression. HNC mortality was found to be positively associated with male sex, past and current smoking habits, moderate-to-heavy alcohol consumption, and being underweight. In addition, serum gamma-glutamyltransferase level was found to be significantly elevated in cases of HNC mortality. In contrast, obesity, a history of diabetes, and fasting blood glucose levels were found to be inversely associated with overall HNC mortality. Among the HNC subtypes, mortality due to laryngeal cancer was most strongly associated with past and heavy cigarette smoking, and mortality due to oro-/hypopharyngeal cancer was most strongly associated with heavy alcohol consumption. The present study demonstrates that this nationwide, population-based NHIS-HEALS data set can provide useful information for health research and policy development.

Chronic Periodontal Disease increases risk for Prostate Cancer in Elderly individuals in South Korea: a Retrospective Nationwide Population-based Cohort Study

Objectives: The association between prostate cancer (PC) and chronic periodontal disease (PD) has been evaluated in previous studies, but results have been inconsistent. This study aimed to determine whether the presence of chronic PD in old age increases the risk of PC using data in the large-scale elderly cohort. Materials and Methods: This nationwide population-based cohort study examined data of 121,240 South Korean individuals aged ≥ 60 years from the National Health Insurance Service-Elderly Cohort database who completed a national program between 2002 and 2015. For a maximum 10 years' observation period, patients with incident PC with chronic PD compared with those without chronic PD were retrospectively tracked, and Cox proportional hazard ratios and 95% confidence intervals (CIs) were calculated, adjusted for potential confounding factors, including age, household income, insurance status, Charlson Comorbidity Index, hypertension, diabetes mellitus, cerebral infarction, angina pectoris, myocardial infarction, prostatitis, smoking status, daily smoking, alcohol intake habits, one-time alcohol intake, and regular exercise. Results: The overall incidence of PC with chronic PD in 10 years was 3.0% (n = 2,063). In the multivariate Cox analysis with adjustment for confounding factors, chronic PD was associated with a 24% higher risk of PC (95% CI = 1.16-1.32, P < 0.001). Conclusion: Our results suggest that chronic PD is significantly and positively associated with PC. Larger and better-controlled studies are needed to strengthen this evidence of association and explain the underlying biological mechanisms.

Periodontitis and oral Cancer-A striking link

Oral squamous cell carcinoma (OSCC) has become a major public health problem in the worldwide for its increasing incidence and mortality, especially in younger trends. Risk factors for OSCC apart from alcohol and tobacco use, include poor oral hygiene, inflammation caused by inadequately fitting dentures and other rough teeth surfaces, poor nutrition and some chronic infections caused by fungi, bacteria or viruses. Several studies have also found that the risk of developing OSCC may increase with periodontal disease (PD). In addition to reduce harm caused by tobacco, alcohol and betel quid it seems prudent to take measures to improve oral hygiene in periodontally compromised patients to minimize OSCC risks. This further intensifies the need for oral health education programs and large cohurt studies to edify individuals about the importance of regular oral health maintenance and routine dental care towards the prevention of oral diseases including OSCC.

Quercetin Inhibits Cell Survival and Metastatic Ability via the EMT-mediated Pathway in Oral Squamous Cell Carcinoma

This study aimed to investigate whether quercetin exerts anticancer effects on oral squamous cell carcinoma (OSCC) cell lines and to elucidate its mechanism of action. These anticancer effects in OSCC cells were assessed using an MTT assay, flow cytometry (to assess the cell cycle), wound-healing assay, invasion assay, Western blot analysis, gelatin zymography, and immunofluorescence. To investigate whether quercetin also inhibits transforming growth factor β1 (TGF-β1)-induced epithelial-mesenchymal transition (EMT) in human keratinocyte cells, HaCaT cells were treated with TGF-β1. Overall, our results strongly suggest that quercetin suppressed the viability of OSCC cells by inducing cell cycle arrest at the G2/M phase. However, quercetin did not affect cell viability of human keratinocytes such as HaCaT (immortal keratinocyte) and nHOK (primary normal human oral keratinocyte) cells. Additionally, quercetin suppresses cell migration through EMT and matrix metalloproteinase (MMP) in OSCC cells and decreases TGF-β1-induced EMT in HaCaT cells. In conclusion, this study is the first, to our knowledge, to demonstrate that quercetin can inhibit the survival and metastatic ability of OSCC cells via the EMT-mediated pathway, specifically Slug. Quercetin may thus provide a novel pharmacological approach for the treatment of OSCCs.

Characteristics and prognosis of primary treatment-naïve oral cavity squamous cell carcinoma in Norway, a descriptive retrospective study

Objectives

Incidence of oral cavity squamous cell carcinomas is rising worldwide, and population characterization is important to follow for future trends. The aim of this retrospective study was to present a large cohort of primary oral cavity squamous cell carcinoma from all four health regions of Norway, with descriptive clinicopathological characteristics and five-year survival outcomes.

Materials and methods

Patients diagnosed with primary treatment-naïve oral cavity squamous cell carcinomas at all four university hospitals in Norway between 2005–2009 were retrospectively included in this study. Clinicopathological data from the electronic health records were compared to survival data.

Results

A total of 535 patients with primary treatment-naïve oral cavity squamous cell carcinomas were identified. The median survival follow-up time was 48 months (range 0–125 months) after treatment. The median five-year overall survival was found to be 47%. Median five-year disease-specific survival was 52%, ranging from 80% for stage I to 33% for stage IV patients. For patients given treatment with curative intent, the overall survival was found to be 56% and disease-specific survival 62%. Median age at diagnosis was 67 years (range 24–101 years), 64 years for men and 72 years for women. The male: female ratio was 1.2. No gender difference was found in neither tumor status (p = 0.180) nor node status (p = 0.266), but both factors influenced significantly on survival (p<0.001 for both).

Conclusions

We present a large cohort of primary treatment-naïve oral cavity squamous cell carcinomas in Norway. Five-year disease-specific survival was 52%, and patients eligible for curative treatment had a five-year disease-specific survival up to 62%.

Potential Salivary mRNA Biomarkers for Early Detection of Oral Cancer

We evaluated potential biomarkers in human whole saliva for the early diagnosis of oral squamous cell carcinoma (OSCC). We selected 30 candidate genes with relevance to cancer from recent reports in PubMed. Saliva samples were obtained from 34 non-tumor control and 33 OSCC patients. Real-time PCR was performed, and mRNA levels were compared. Normalized mRNA levels of six genes (NGFI-A binding protein 2 (NAB2), cytochrome P450, family 27, subfamily A, polypeptide 1 (CYP27A1), nuclear pore complex interacting protein family, member B4 (NPIPB4), monoamine oxidase B (MAOB), sialic acid acetyltransferase (SIAE), and collagen, type III, alpha 1 (COL3A1)) were significantly lower in saliva of OSCC patients. Receiver operating characteristics (ROC) analysis was used to individually evaluate the predictive power of the potential biomarkers for OSCC diagnosis. The area under the curve (AUC) values were evaluated for the OSCC vs. non-tumor groups via univariate ROC analyses, as well as multivariate ROC analyses of combinations of multiple potential biomarkers. The combination of CYP27A1 + SIAE showed a favorable AUC value of 0.84. When we divided saliva samples into two groups according to age using a 60-year cut-off, with OSCC patients and controls evaluated together, the AUC of MAOB-NAB2 was more predictive of OSCC in the under-60 group (AUC, 0.91; sensitivity, 0.92; and specificity, 0.86) than any other gene combination. These results are expected to aid the early diagnosis of OSCC, especially in patients under 60 years of age. While more studies with larger numbers of patients are necessary, our result suggest that salivary mRNA would be a potent biomarker for early OSCC diagnosis.

The Oral Microbiome and Cancer

There is mounting evidence that members of the human microbiome are highly associated with a wide variety of cancer types. Among oral cancers, oral squamous cell carcinoma (OSCC) is the most prevalent and most commonly studied, and it is the most common malignancy of the head and neck worldwide. However, there is a void regarding the role that the oral microbiome may play in OSCC. Previous studies have not consistently found a characteristic oral microbiome composition associated with OSCC. Although a direct causality has not been proven, individual members of the oral microbiome are capable of promoting various tumorigenic functions related to cancer development. Two prominent oral pathogens, Porphyromonas gingivalis, and Fusobacterium nucleatum can promote tumor progression in mice. P. gingivalis infection has been associated with oro-digestive cancer, increased oral cancer invasion, and proliferation of oral cancer stem cells. The microbiome can influence the evolution of the disease by directly interacting with the human body and significantly altering the response and toxicity to various forms of cancer therapy. Recent studies have shown an association of certain phylogenetic groups with the immunotherapy treatment outcomes of certain tumors. On the other side of the coin, recently it has been a resurgence in interest on the potential use of bacteria to cure cancer. These kinds of treatments were used in the late nineteenth and early twentieth centuries as the first line of defense against cancer in some hospitals but later displaced by other types of treatments such as radiotherapy. Currently, organisms such as Salmonella typhimurium and Clostridium spp. have been used for targeted strategies as potential vectors to treat cancer. In this review, we briefly summarize our current knowledge of the role of the oral microbiome, focusing on its bacterial fraction, in cancer in general and in OSCC more precisely, and a brief description of the potential use of bacteria to target tumors.

Celecoxib suppresses lipopolysaccharide-stimulated oral squamous cell carcinoma proliferation in vitro and in vivo

Periodontitis is one of the most common chronic oral inflammatory conditions worldwide and is associated with a risk of developing oral squamous cell carcinoma (OSCC). Porphyromonas gingivalis is a major pathogen in periodontitis, and its lipopolysaccharide (LPS) promotes the expression of cyclooxygenase-2 (COX-2) in OSCC both in vivo and in vitro. Celecoxib is a selective COX-2 inhibitor; however, its antitumor effects on P. gingivalis LPS-stimulated OSCC and the underlying molecular mechanism remain unclear. To elucidate the association between periodontitis and OSCC, the effect of P. gingivalis-derived LPS on OSCC cell proliferation was examined both in vitro and in vivo in the present study. The expression levels of COX-2 and p53 in OSCC cells with/without celecoxib treatment were determined via western blotting. The therapeutic potential of celecoxib in LPS-stimulated OSCC was evaluated by staining for Ki-67 and p21, as well as with terminal deoxynucleotidyl-transferase-mediated dUTP nick end labeling staining. LPS treatment significantly increased OSCC cell proliferation in vitro, and celecoxib significantly inhibited cell proliferation with/without LPS treatment. Celecoxib treatment of OSCC cells downregulated the protein expression levels of COX-2 compared with untreated cells, but there was little change in p53 expression. In the mouse xenograft model, oral administration of celecoxib significantly suppressed tumor growth, reduced the expression of Ki-67, increased the apoptosis index and induced p21 expression with/without LPS treatment. The results from the present study demonstrate that P. gingivalis' LPS can stimulate tumor growth by interacting with OSCC cells. In conclusion, these results suggest that celecoxib could be used for the effective prevention and treatment of LPS-stimulated OSCC.

Role of Porphyromonas gingivalis in oral squamous cell carcinoma development: A systematic review

OBJECTIVE

The target of the current systematic review is to gather and synthesize the most recent scientific information about the role of Porphyromonas gingivalis in the molecular pathways of oral squamous cell carcinoma (OSCC).

BACKGROUND

Oral squamous cell carcinoma is the most common malignancy of the oral cavity, with a poor prognosis and a low survival rate. Etiology is multifactorial but consumption of tobacco and alcohol is the most important risk factors. P gingivalis is a Gram-negative anaerobic bacterium commonly found in oral microbiota that has been linked to periodontal disease (PD), and recently to OSCC. However, its association with OSCC development is not well defined.

MATERIAL AND METHODS

A bibliographic research was carried out selecting articles published until 2019, on PubMed, Web of Science, and Scopus databases, with the keywords "Porphyromonas gingivalis," "oral cancer," "oral squamous cell carcinoma," and "periodontal pathogen."

RESULTS

Seventeen articles, 14 in vitro and three in animal models, were selected. Models mimicking OSCC were OSCC pre-established cell lines (11 studies), OSCC/ healthy human biopsies (three studies), and animals with OSCC (three studies). P gingivalis strains used to cause infection in these studies were ATCC 33277, 381, and W83.

CONCLUSIONS

Porphyromonas gingivalis could play an important role in OSCC development and could be involved in three different stages: epithelial-mesenchymal transition of malignant cells, neoplastic proliferation, and tumor invasion. Current findings emphasize the convenience of treatment and control approaches of PD as part of the primary prevention of OSCC.

The Highly Pure Neem Leaf Extract, SCNE, Inhibits Tumorigenesis in Oral Squamous Cell Carcinoma via Disruption of Pro-tumor Inflammatory Cytokines and Cell Signaling

Oral squamous cell carcinoma (OSCC) is a deadly disease that comprises 60% of all head and neck squamous cell cancers. The leaves of the Neem tree (Azadirachta indica) have been used in traditional Ayurvedic medicine for centuries to treat numerous oral maladies and are known to have significant anti-inflammatory properties. We hypothesize that a highly pure super critical CO2 Neem leaf extract (SCNE) prevents initiation and progression of OSCC via downregulation of intra-tumor pro-inflammatory pathways, which promote tumorigenesis. Hence, we investigated the anticancer effects of SCNE using in vitro and in vivo platforms. OSCC cell lines (SCC4, Cal27, and HSC3) were treated with SCNE while inflammation, proliferation, and migration were analyzed over time. SCNE treatment significantly inhibited OSCC cell proliferation and migration and reduced MMP activity in vitro, suggesting its potential to inhibit tumor growth and metastasis. The preventive effects of SCNE in ectopic xenograft and 4NQO-1 (4-Nitroquinoline-1-oxide) carcinogen-induced mouse models of OSCC were also evaluated. Indeed, xenografted nude mice showed significant reduction of OSCC tumor volumes. Likewise, SCNE significantly reduced the incidence of tongue dysplasia in the 4NQO-1 OSCC initiation model. In both OSCC animal models, SCNE significantly depressed circulating pro-cancer inflammatory cytokines (host and tumor-secreted) including NFkB, COX2, IL-1, IL-6, TNFα, and IFNγ. In addition, we demonstrate that SCNE downregulates STAT3 and AKT expression and activity in vitro. We also demonstrate that the primary active component, nimbolide (NIM), has significant anticancer activity in established OSCC xenografts. Lastly, we show that SCNE induces an M1 phenotype in tumor associated macrophages (TAMS) in vivo. Taken together, these data strongly support SCNE as means of preventing OSCC via downregulation of pro-cancer inflammatory cascades and NIM as a potential new therapy for existing OSCC.

Awareness of the Relationship between Systemic and Periodontal Diseases among Physicians and Dentists in Saudi Arabia and Kuwait: Cross-sectional Study

Background:

Previous studies have shown possible association between periodontal diseases and Diabetes Mellitus (DM), Cardiovascular Disease (CVD) and Adverse Pregnancy Outcomes (APO). Increasing the knowledge of physicians and dentists regarding the association between periodontal disease and systemic diseases should improve their ability to provide a high standard of treatment for the disease and prevent its consequences. In our study, we sought to identify knowledge gaps in the awareness of the relationship between systemic and periodontal diseases among dentists and physicians from the Kingdom of Saudi Arabia and the State of Kuwait.

Methods:

A cross-sectional study was performed with a convenient sample of selected physicians and dentists in Saudi Arabia and Kuwait using a self-developed structured questionnaire. Physicians’ and dentists’ awareness were assessed regarding current evidence of the relationship between systemic diseases and conditions (DM, CVD, APO) and periodontal diseases.

Results:

A total of 134 (21.5%) of the identified physicians and 485 (78%) of the identified dentists participated in this study. More than half of the participants (52.1% physicians and 67.5% dentists) agreed that there is a relationship between periodontal diseases and DM, CVD and APO. Dentists had a statistically higher level of awareness compared with the physicians. The findings related to the awareness of the dentist sub groups highlighted that periodontists were significantly more likely to have a good level of knowledge.

Conclusion:

Within the limitations of this study, we concluded that the awareness of physicians and dentists regarding the relationship between periodontal diseases and systemic diseases (DM, CVD, APO) is generally low, Therefore, improved collaboration between medical and dental health providers is recommended.