Association between Tooth Loss and Gastric Cancer: A Meta-Analysis of Observational Studies

Fusobacterium nucleatum: Unraveling its potential role in gastric carcinogenesis

Fusobacterium nucleatum (F. nucleatum) is a Gram-negative anaerobic bacterium that plays a key role in the development of oral inflammation, such as periodontitis and gingivitis. In the last 10 years, F. nucleatum has been identified as a prevalent bacterium associated with colorectal adenocarcinoma and has also been linked to cancer progression, metastasis and poor disease outcome. While the role of F. nucleatum in colon carcinogenesis has been intensively studied, its role in gastric carcinogenesis is still poorly understood. Although Helicobacter pylori infection has historically been recognized as the strongest risk factor for the development of gastric cancer (GC), with recent advances in DNA sequencing technology, other members of the gastric microbial community, and F. nucleatum in particular, have received increasing attention. In this review, we summarize the existing knowledge on the involvement of F. nucleatum in gastric carcinogenesis and address the potential translational and clinical significance of F. nucleatum in GC.

Epidemiological associations between periodontitis and cancer

There is a postulated association of periodontitis with a number of human cancers. This narrative review provides current epidemiological evidence on the association between periodontitis and cancer. A PubMed search with the relevant keywords (periodontal disease, periodontitis, cancer, and malignancy) was completed to identify relevent articles. We present a narrative review on the association between periodontal disease and a range of cancers, including oral cancer, stomach and esophageal cancer, colorectal cancer, lung cancer, pancreatic cancer, prostate cancer, hematological malignancies, liver cancer, breast cancer, and ovarian cancer. While there is a considerable body of epidemiological evidence that supports the association between periodontal disease and cancer, this is largely from cohort and case-control studies and the association may therefore be circumstantial as little evidence exists in the form of treatment trials that would validate the role of periodontal disease in the process of cancer initiation and development.

Porphyromonas gingivalis, a bridge between oral health and immune evasion in gastric cancer

Porphyromonas gingivalis (P. gingivalis) is a gram-negative oral pathogen associated with chronic periodontitis. Previous studies have linked poor oral health and periodontitis with oral cancer. Severe cases of periodontal disease can result in advanced periodontitis, leading to tissue degradation, tooth loss, and may also correlate with higher gastric cancer (GC) risk. In fact, tooth loss is associated with an elevated risk of cancer. However, the clinical evidence for this association remains inconclusive. Periodontitis is also characterized by chronic inflammation and upregulation of members of the Programmed Death 1/PD1 Ligand 1 (PD1/PDL1) axis that leads to an immunosuppressive state. Given that chronic inflammation and immunosuppression are conditions that facilitate cancer progression and carcinogenesis, we hypothesize that oral P. gingivalis and/or its virulence factors serve as a mechanistic link between oral health and gastric carcinogenesis/GC progression. We also discuss the potential impact of P. gingivalis' virulence factors (gingipains, lipopolysaccharide (LPS), and fimbriae) on inflammation and the response to immune checkpoint inhibitors in GC which are part of the current standard of care for advanced stage patients.

The role of microbiota in gastric cancer: A comprehensive review

BACKGROUND

Gastric cancer (GC) continues to pose a significant global threat in terms of cancer-related fatalities. Despite notable advancements in medical research and therapies, further investigation is warranted to elucidate its underlying etiology and risk factors. Recent times have witnessed an escalated emphasis on comprehending the role of the microbiota in cancer development.

METHODS

This review briefly delves into recent developments in microbiome-related research pertaining to gastric cancer.

RESULTS

According to studies, the microbiota can influence GC growth by inciting inflammation, disrupting immunological processes, and generating harmful microbial metabolites. Furthermore, there is ongoing research into how the microbiome can impact a patient's response to chemotherapy and immunotherapy.

CONCLUSION

The utilization of the microbiome for detecting, preventing, and managing stomach cancer remains an active area of exploration.

Changes in salivary microbiota due to gastric cancer resection and its relation to gastric fluid microbiota

Gastric cancer is one of the leading causes of death worldwide, and resections are performed to cure the disease. We have previously reported the changes in the gastric microbiota after gastric cancer resection, which may be associated with the oral microbiota; however, the changes in the oral microbiota remain uncharacterized. This study aimed to characterize the changes in the salivary microbiota caused by gastric cancer resection and to evaluate their association with the gastric fluid microbiota. Saliva and gastric fluid samples were collected from 63 patients who underwent gastrectomy before and after surgery, and a 16S rRNA metagenomic analysis was performed to compare the microbiota composition. The number of bacterial species in the salivary microbiota decreased, and the bacterial composition changed after the resection of gastric cancer. In addition, we identified several bacterial genera that varied significantly in the salivary microbiota, some of which also showed similar changes in the gastric fluid microbiota. These findings indicate that changes in the gastric environment affect the oral microbiota, emphasizing the close association between the oral and gastric fluid microbiota. Our study signifies the importance of focusing on the oral microbiota in the perioperative period of gastrectomy in patients with gastric cancer.

The analysis of periodontal diseases and squamous cell esophageal cancer: A retrospective study

Aim

The potential links between periodontal disease and various cancers have drawn more and more attention in recent years. The objective of the current study was to investigate any potential associations between parameters of periodontal disease, the number of teeth lost, and the risk of developing squamous cell esophageal cancer in a representative adult sample.

Materials and Methods

The study sample included 178 healthy individuals with matched age and socioeconomic status as controls and 60 patients with the primary histological type of esophageal cancer, Squamous Cell Esophageal Cancer. Data were collected from cases and controls on epidemiological factors like age, gender, smoking status, alcohol intake, socio-economic status, level of education, and prior medical/dental history. The clinical data on periodontal health status was obtained through a clinical examination. This data concerned Probing Pocket Depth (PPD), Clinical Attachment Loss (CAL), the number of teeth lost, and the common risk factors for Squamous Cell Esophageal Carcinoma. Additionally, univariate, and logistic regression models that were modified for potential confounders were used to estimate unadjacent and adjacent odds ratios (ORs) and 95% confidence intervals (CIs).

Results

Lower socioeconomic status (p = 0.048) (OR = 1.882, 95% CI = 0.987-3.591), smoking (p = 0.052) (OR = 1.768, 95% CI = 0.931-3.359), moderate and heavy alcohol abuse (p = 0.035) (OR = 1.880, 95% CI = 0.987 3.579), and irregular tooth brushing frequency (p = 0.001) (OR = 0.326, 95% CI = 0.171-0.619) were indeed discovered to be significantly linked.

Conclusion

Individuals with lower socio-economic status, smoking, moderate and heavy alcohol consumption, and irregular tooth brushing frequency were significantly associated with Periodontal diseases and Squamous Cell Esophageal Cancer.

Chronic Periodontitis and the Potential Likelihood of Gastric Cancer: A Nested Case-Control Study in the Korean Population Utilizing a National Health Sample Cohort

There is limited information regarding the potential association between chronic periodontitis (CP) and gastric cancer, especially in the Korean population. This study aimed to explore this relationship. This nested case-control study analyzed data from 10,174 patients with gastric cancer and 40,696 controls from the Korean National Health Insurance Service-National Sample Cohort using propensity score matching. Standardized differences were used to compare baseline characteristics between study groups. Logistic regression analyses adjusted for confounders were conducted to assess the association between history of CP and gastric cancer occurrence. CP histories and comprehensive subgroup analyses in the 1- and 2-year periods preceding the index date were evaluated. Individuals with a history of CP within the 1-year and 2-year periods showed an increased likelihood of developing gastric cancer. Subgroup analyses consistently supported these findings in male participants aged <65 years and individuals with various income levels or living in residential areas. However, no significant associations were observed among participants aged ≥65 years. In conclusion, CP may be a potential risk factor for gastric cancer development in the Korean population. Regular screening for gastric cancer may be necessary for high-risk individuals, specifically men aged <65 years with a history of CP.

Risk factors for gastric cancer: A comprehensive analysis of observational studies

Background

Multifarious factors have a causal relationship with gastric cancer (GC) development. We conducted a comprehensive analysis to evaluate the strength of the evidence examining non-genetic risk factors for gastric cancer.

Methods

PubMed, Web of Science, and the Cochrane Library were searched from inception to November 10, 2021 to identify meta-analyses of observational studies examining the association between environmental factors and GC risk. For each meta-analysis, the random effect size, 95% confidence interval, heterogeneity among studies, and evidence of publication bias were assessed; moreover, the evidence was graded using predefined criteria, and the methodological quality was evaluated using AMSTAR 2.

Results

A total of 137 associations were examined in 76 articles. Among these meta-analyses, 93 associations yielded significant estimates (p < 0.05). Only 10 associations had strong epidemiologic evidence, including 2 risk factors (waist circumference and bacon), and 8 protective factors (dietary total antioxidant capacity, vegetable fat, cruciferous vegetable, cabbage, total vitamin, vitamin A, vitamin C, and years of fertility); 26 associations had moderate quality of evidence; and the remaining 57 associations were rated as weak. Ninety-four (68.61%) associations showed significant heterogeneity. Twenty-five (18.25%) associations demonstrated publication bias.

Conclusions

In this comprehensive analysis, multiple associations were found between environmental factors and GC with varying levels of evidence. Healthy dietary habits and lifestyle patterns could reduce the risk for GC. However, further high-quality prospective studies are still necessary to draw more definitive conclusions.

Meta-analysis of mucosal microbiota reveals universal microbial signatures and dysbiosis in gastric carcinogenesis

The consistency of the associations between gastric mucosal microbiome and gastric cancer across studies remained unexamined. We aimed to identify universal microbial signatures in gastric carcinogenesis through a meta-analysis of gastric microbiome from multiple studies. Compositional and ecological profiles of gastric microbes across stages of gastric carcinogenesis were significantly altered. Meta-analysis revealed that opportunistic pathobionts Fusobacterium, Parvimonas, Veillonella, Prevotella and Peptostreptococcus were enriched in GC, while commensals Bifidobacterium, Bacillus and Blautia were depleted in comparison to SG. The co-occurring correlation strengths of GC-enriched bacteria were increased along disease progression while those of GC-depleted bacteria were decreased. Eight bacterial taxa, including Veillonella, Dialister, Granulicatella, Herbaspirillum, Comamonas, Chryseobacterium, Shewanella and Helicobacter, were newly identified by this study as universal biomarkers for robustly discriminating GC from SG, with an area under the curve (AUC) of 0.85. Moreover, H. pylori-positive samples exhibited reduced microbial diversity, altered microbiota community and weaker interactions among gastric microbes. Our meta-analysis demonstrated comprehensive and generalizable gastric mucosa microbial features associated with histological stages of gastric carcinogenesis, including GC associated bacteria, diagnostic biomarkers, bacterial network alteration and H. pylori influence.

The Need for Oral Hygiene Care and Periodontal Status among Hospitalized Gastric Cancer Patients

Poor oral hygiene leads to the accumulation of dental plaque, thus contributing to the initiation of periodontal disease (PD). Local infections can lead to systemic inflammatory responses, which are essential mediators for the evolution of systemic conditions or cancer tumorigenesis. Often, patients hospitalized with life-threatening and incapacitating disorders such as gastric cancer (GC) might lose interest in keeping their mouth healthy. This study evaluates oral hygiene, periodontal status, and the need for oral care and medical personnel to assist in achieving it in patients hospitalized with GC. This study was carried out on 25 patients with a diagnosis of GC, divided into two groups (GP-14 patients from the Gastroenterology Department, and SP-11 patients from the 1st Department of Surgery). Patients were examined on the day of admission (T0), the day of the medical procedure of endoscopy or surgery (T1), and the day of discharge (T2), recording the number of absent teeth, dental plaque (PI), bleeding on probing (BOP), probing depths (PPD), frequency of toothbrushing, and if the oral hygiene had been self-performed or assisted. Data were subjected to statistical analysis. Our results showed that, in both the GP and the SP group, there were strong and statistically significant correlations between PI and BOP measured on the last day of hospitalization and the period of hospitalization after the medical procedure. Longer hospital stays and the presence of surgery were risk factors for changing toothbrushing frequency. Results also highlight the need for a dentist to diagnose and eventually treat periodontal disease before and after hospitalization, and for a trained nurse who should help take care of the patient's oral hygiene during hospitalization.

Subgingival Periopathogens Assessment and Clinical Periodontal Evaluation of Gastric Cancer Patients—A Cross Sectional Pilot Study

Oral microbiota have shown a higher bacterial diversity in patients with cancers of the digestive tract, with higher levels of periopathogens. Recent studies have shown that Fusobacterium links to gastro-intestinal neoplastic tissue and accelerates its progression, as well as worsening patient outcome. The present pilot study was carried out between February and December 2020 to evaluate the possible association between the abundance of some periopathogens (Fusobacterium nucleatum, Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Treponema denticola and Tannerella forsythia) in subgingival plaque and periodontal status with characteristics of gastric cancer. The study was performed on a sample of 24 patients with gastric cancer from the 1st Department of Surgery and Department of Gastroenterology within the Clinical County Hospital of Emergency of Craiova, Romania. The patients’ oral cavity was examined, gingival crevicular samples were collected, and signs of periodontal disease were recorded. On the histopathological exam, the differentiation grade and size of the tumour were registered. Our results showed that, from the periopathogens studied, the most abundant bacteria were F. nucleatum followed by T. forsythia in all groups. In our present study, the strong correlation between tumour dimension and all periodontal parameters but also between tumour dimension and F. nucleatum could suggest a positive association between periodontal disease, tumoral growth and periopathogens implication in this process.

Gastric microbiota composition in patients with corpus atrophic gastritis

BACKGROUND

In corpus atrophic gastritis (CAG), hypochlorhydria makes plausible the overgrowth of intragastric bacteria, whose role in gastric carcinogenesis is under debate.

AIMS

To characterize the antrum/corpus composition of the gastric bacterial microbiota in CAG patients compared to controls without CAG.

METHODS

A cross-sectional monocentric study on consecutive patients with known histological diagnosis of CAG undergoing gastroscopy for gastric cancer surveillance and patients without CAG undergoing gastroscopy for dyspepsia or anemia (108 biopsies from 55 patients, median age 61.5). Genomic DNA from one antral and one corpus biopsy from each case (n = 23) and control (n = 32) was extracted. Gastric microbiota was assessed by sequencing hypervariable regions of the 16SrRNA gene.

RESULTS

Bacterial abundance and diversity were significantly lower in CAG cases than in controls (p < 0.001). Firmicutes were more frequent in cases, Bacteroidetes and Fusobacteria in controls (p < 0.0001). Streptococcaceae were more abundant in cases (p < 0.0001), Prevotellaceae in controls (p < 0.0001). The genus Streptococcus was positively correlated with severe OLGA/OLGIM stages linked to a higher risk of gastric cancer.

CONCLUSION

Gastric bacterial microbiota in CAG showed a reduced abundance and complexity but was characterized by higher colonization of Firmicutes, in particular Streptococcus, increased in subjects with severe atrophy/metaplasia stages at higher risk of gastric cancer.

Tooth retention predicts good physical performance in older adults

BACKGROUND

Oral health is closely related to both physical and psychological well-being, as it enables individuals to eat, speak, and socialize. The number of teeth is the most used indicator of oral health. Several reports document a relationship of dental status with a variety of indicators of general health but longitudinal studies employing standardized physical performance tests are infrequent in the scientific literature.

SUBJECTS AND METHODS

The Italian elderly participating in the Pro.V.A. longitudinal Study (3099 subjects aged 65+ at baseline, 2196 at the 5-year follow-up 1 and 1641 at the 7-year follow- up 2) underwent detailed interview and extensive clinical and instrumental examination that included validated physical performance measures. Participants were classified into 4 groups according to the number of remaining teeth: 0, 1-7, 8-19, and 20+. To explore the association of the number of remaining teeth with physical function and disability, we performed logistic regression analyses with models progressively adjusted for a wide number of covariates, namely anthropometric (gender, age, BMI), comorbidity (cardio-vascular, osteoarticular, and neurological diseases including depression), muscle strength (assessed for upper and lower limbs), lifestyle (smoking status, alcohol use, leisure time activities) and socioeconomical status (education, income, marital status, loneliness).

RESULTS

Dental status correlated with most comorbidities, lifestyle, and socio-economic variables at the univariate analysis at baseline and at follow-ups. A good dental status was significantly associated with better physical functioning and lower disability. The presence of 20+ teeth resulted significantly protective (reference group: 0 teeth) versus mobility-related disability (OR = 0.67), disability (OR = 0.54) and inability to perform heavy duties (OR = 0.62), at follow up 1 and low physical performance score (OR = 0.59) at follow up 2. Conversely, the detrimental effect of edentulism, explored in subjects with or without dentures, was present but not as straightforward. Conclusion. The assessment of a geriatric patient should include an oral evaluation as a good dental status is a crucial component of successful aging.

Paradigm shift in the pathogenesis and treatment of oral cancer and other cancers focused on the oralome and antimicrobial-based therapeutics

The oral microbiome is a community of microorganisms, comprised of bacteria, fungi, viruses, archaea, and protozoa, that form a complex ecosystem within the oral cavity. Although minor perturbations in the environment are frequent and compensable, major shifts in the oral microbiome can promote an unbalanced state, known as dysbiosis. Dysbiosis can promote oral diseases, including periodontitis. In addition, oral dysbiosis has been associated with other systemic diseases, including cancer. The objective of this review is to evaluate the epidemiologic evidence linking periodontitis to oral, gastrointestinal, lung, breast, prostate, and uterine cancers, as well as describe new evidence and insights into the role of oral dysbiosis in the etiology and pathogenesis of the cancer types discussed. Finally, we discuss how antimicrobials, antimicrobial peptides, and probiotics may be promising tools to prevent and treat these cancers, targeting both the microbes and associated carcinogenesis processes. These findings represent a novel paradigm in the pathogenesis and treatment of cancer focused on the oral microbiome and antimicrobial‐based therapies.

The Cancer Microbiome: Recent Highlights and Knowledge Gaps

Knowledge of the human microbiome, which is likely a critical factor in the initiation, progression, and prognosis of multiple forms of cancer, is rapidly expanding. In this review, we focus on recent investigations to discern putative, causative microbial species and the microbiome composition and structure currently associated with procarcinogenesis and tumorigenesis at select body sites. We specifically highlight forms of cancer, gastrointestinal and nongastrointestinal, that have significant bacterial associations and well-defined experimental evidence with the aim of generating directions for future experimental and translational investigations to develop a clearer understanding of the multifaceted mechanisms by which microbiota affect cancer formation. SIGNIFICANCE: Emerging and, for some cancers, strong experimental and translational data support the contribution of the microbiome to cancer biology and disease progression. Disrupting microbiome features and pathways contributing to cancer may provide new approaches to improving cancer outcomes in patients.

Autoimmune Gastritis and Gastric Microbiota

Autoimmune atrophic gastritis is an organ-specific immune-mediated condition characterized by atrophy of the oxyntic mucosa. Autoimmune atrophic gastritis (AIG) is characterized by a progressive loss of acid-secreting parietal cells leading to hypo-achlorhydria. Due to this peculiar intra-gastric environment, gastric microbiota composition in individuals with autoimmune atrophic gastritis was first supposed and then recently reported to be different from subjects with a normal acidic healthy stomach. Recent data confirm the prominent role of Helicobacter pylori as the main bacterium responsible for gastric disease and long-term complications. However, other bacteria than Helicobacter pylori, for example, Streptococci, were found in subjects who developed gastric cancer and in subjects at risk of this fearful complication, as well as those with autoimmune gastritis. Gastric microbiota composition is challenging to study due to the acidic gastric environment, the difficulty of obtaining representative samples of the entire gastric microbiota, and the possible contamination by oral or throat microorganisms, which can potentially lead to the distortion of the original gastric microbial composition, but innovative molecular approaches based on the analysis of the hyper-variable region of the 16S rRNA gene have been developed, permitting us to obtain an overall microbial composition view of the RNA gene that is present only in prokaryotic cells.

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.

Correlation between prognostic nutritional index and occlusal status in gastric cancer

OBJECTIVE

Systemic inflammatory responses in cancer patients are important factors for nutrition and prognosis. This study evaluates the association between tooth loss, occlusal status, and prognostic nutritional index (PNI).

METHODS

A total of 93 patients with gastric cancer were included. These parameters were investigated the following: stage, body mass index (BMI), total lymphocyte count, C-reactive protein (CRP), PNI, and albumin (ALB). Patients were divided into three groups by Eichner classification (group A had contact in four support zones; group B had in one to three zones or in anterior region; and group C had no contact). PNI assumed 40 or less undernutrition. Multiple regression analysis was performed (PNI, dependent variable; Eichner index, main independent variable), using four independent variables (sex, age, BMI, and CRP) as adjustment factors.

RESULTS

The mean ± SD PNI in groups A, B, and C was 43.0 ± 4.7, 41.7 ± 5.2, and 36.7 ± 7.7, respectively. A significant positive correlation was found between the number of teeth, both ALB, and PNI. ALB and PNI differed significantly between groups A and C (ALB, p = .0003; PNI, p = .005).

CONCLUSION

We recommend a preoperative dental evaluation for assessing the nutritional status of patients with gastric cancer.

The potential role of P.gingivalis in gastrointestinal cancer: a mini review

Bacterial infection may be involved in the entire process of tissue carcinogenesis by directly or indirectly affecting the occurrence and development of tumors. Porphyromonas gingivalis (P.gingivalis) is an important pathogen causing periodontitis. Periodontitis may promote the occurrence of various tumors. Gastrointestinal tumors are common malignant tumors with high morbidity, high mortality, and low early diagnosis rate. With the rapid development of molecularbiotechnology, the role of P.gingivalis in digestive tract tumors has been increasingly explored. This article reviews the correlation between P.gingivalis and gastrointestinal cancer and the pathogenesis of the latter. The relationship among P.gingivalis, periodontal disease, and digestive tract tumors must be clarifiedthrough a multi-center, prospective, large-scale study.

Validity of the self-reported number of teeth in Chilean adults

Background

Clinical dental evaluations are considered complex and costly measurements that epidemiological surveillance studies of multiple simultaneous chronic diseases currently require, for example National Health Surveys (ENS). Accordingly, simpler and more affordable methods need to be validated. The aim of this study was to assess the validity of the self-report on the total number of teeth in the general Chilean adult population.

Methods

A substudy was conducted on ENS 2016–2017 participants. A stratified random sample of 101 of them was subjected to a telephone questionnaire. This information was then compared with the results obtained from the oral examination performed by a trained nurse during a home visit. Spearman correlations, intraclass correlation coefficients and the Bland-Altman method were used to analyse the data.

Results

In men, the average number of teeth recorded during the oral examination coincided with the number of teeth in the self-report (22 teeth). In women, the total teeth average was 18 and 19 teeth according to the examination and self-report, respectively. For the total number of participants, a strong and significant Spearman correlation was obtained (ρ = 0.93); in men and women, the Spearman correlation observed was also strong and significant (ρ = 0.90 and ρ = 0.96 respectively). The value of the intraclass correlation coefficient indicated a significant concordance (CCI = 0.96) in both men and women (CCI = 0.93 and 0.98 respectively). A tendency to greater correlation was observed as the number of teeth decreased.

Conclusions

The number of teeth self-reported by the subjects in this study correlated with the number of teeth recorded in the clinical examination. Self-report is a valid method to determine the number of teeth in national health surveys.

Porphyromonas gingivalis and digestive system cancers

Porphyromonas gingivalis (P. gingivalis) is an anaerobic gram-negative bacterium that colonizes in the epithelium and has been strongly associated with periodontal disease. Recently, various degrees of associations between P. gingivalis and digestive system cancers, including oral squamous cell carcinoma in the oral cavity, oesophageal squamous carcinoma in the digestive tract, and pancreatic cancer in pancreatic tissues, have been displayed in multiple clinical and experimental studies. Since P. gingivalis has a strong association with periodontal diseases, not only the relationships between P. gingivalis and digestive system tumours but also the effects induced by periodontal diseases on cancers are well-illustrated in this review. In addition, the prevention and possible treatments for these digestive system tumours induced by P. gingivalis infection are also included in this review. At the end, we also highlighted the possible mechanisms of cancers caused by P. gingivalis. One important carcinogenic effect of P. gingivalis is inhibiting the apoptosis of epithelial cells, which also plays an intrinsic role in protecting cancerous cells. Some signalling pathways activated by P. gingivalis are involved in cell apoptosis, tumourigenesis, immune evasion and cell invasion of tumour cells. In addition, metabolism of potentially carcinogenic substances caused by P. gingivalis is also one of the connections between this bacterium and cancers.

Association between tooth loss and upper gastrointestinal cancer: A 30-year follow-up of the Linxian Dysplasia Nutrition Intervention Trial Cohort

Background

This prospective study investigated the association between tooth loss and upper gastrointestinal (UGI) cancer mortality in the Linxian Dysplasia Nutrition Intervention Trial Cohort.

Methods

Subjects were categorized into three groups according to age at baseline. No missing teeth and less or greater than median tooth loss in each group was defined as none, moderate, and severe, respectively. Hazard ratios (HRs) and 95% confidence intervals (95% CIs) were estimated using the Cox proportional hazard model.

Results

Through 30 September 2015, 541 esophageal squamous cell carcinoma (ESCC), 284 gastric cardia carcinoma (GCC), and 77 gastric non‐cardia carcinoma (GNCC) deaths occurred. In the six‐year follow‐up, severe tooth loss was associated with an increased risk of GCC mortality (HR 1.55, 95% CI 1.06–2.18). In the 15‐year follow‐up, moderate tooth loss increased the ESCC mortality risk by 58% (HR 1.58, 95% CI 1.06–2.35), while severe loss increased the GCC mortality risk by 30% (HR 1.30, 95% CI 1.03–1.64). In the 30‐year follow‐up, moderate tooth loss increased the risk of ESCC mortality (HR 1.34, 95% CI 1.01–1.76). In subjects aged < 55 at baseline and men, moderate tooth loss had 53% and 52% higher risks of ESCC mortality (HR_{<55 years} 1.53, 95% CI 1.06–2.05; HRmen 1.52, 95% CI 1.01–2.28). No significant association was observed for GNCC in any subjects or subgroups.

Conclusion

Moderate tooth loss increased the risk of ESCC mortality, particularly in younger subjects and men. Severe tooth loss increased the risk of GCC mortality. Future studies are needed to confirm these findings.

The relationship between tooth loss and mortality from all causes, cardiovascular diseases, and coronary heart disease in the general population: systematic review and dose-response meta-analysis of prospective cohort studies

Background: The association of tooth loss with mortality from all causes, cardiovascular diseases (CVD), and coronary heart disease (CHD) has been studied for many years; however, the results are inconsistent.

Method: PubMed, Embase, Web of Knowledge, and Cochrane Oral Health Group’s Trials Register databases were searched for papers published from 1966 to August 2018. We conducted dose–response meta-analysis to quantitatively evaluate the relation between tooth loss and risk of mortality from all causes, CVD, and CHD.

Results: In the present study, 18 prospective studies conducted until August 2018 were considered eligible for analysis. In the analysis of linear association, the summarized relative risk (RR) values for each 10-, 20-, and 32-tooth loss for all-cause mortality were 1.15 (1.11–1.19), 1.33 (1.23–1.29), and 1.57 (1.39–1.51), respectively. Subgroup and sensitivity analyses showed consistent results. A linear relationship was found among all-cause mortality, with P_nonlinearity = 0.306. The susceptibility to all-cause mortality increased by almost 1.48 times at very high tooth loss (28–32), and slight flattening of the curve was noted. However, the summarized RR values for increment for 10-, 20-, and 32-tooth loss were not or were marginally related to increased risk of mortality from CVD/CHD. Subgroup and sensitivity analyses revealed inconsistent results. Tooth loss showed linear association with CHD mortality but not with CVD mortality. The susceptibility to all-cause mortality increased by almost 1.48 and 1.70 times for CVD and CHD, respectively, at very high tooth loss (28–32). The curve exhibited slight flattening; however, no statistical significance was detected.

Conclusion: In the meta-analysis, our findings confirmed the positive relationship between tooth loss and susceptibility to all-cause mortality, but not for circulatory mortality. However, the finding that tooth loss might play a harmful role in the development of all-cause mortality remains inconclusive. Tooth loss may be a potential risk marker for all-cause mortality: however, their association must be further validated through large prospective studies.

Periodontal Disease and Breast Cancer: A Meta-Analysis of 1,73,162 Participants

Objective: To investigate the correlation between periodontal disease and breast cancer. Materials and Methods: PubMed and China National Knowledge Infrastructure (CNKI) databases were searched up to February 8, 2018 for observational studies examining the association between periodontal disease and breast cancer. Study selection was conducted according to predesigned eligibility criteria, and two authors independently extracted data from included studies. Meta-analysis was performed using the Comprehensive Meta-Analysis v2 software and risk estimates were calculated as relative risks (RRs) with corresponding 95% confidence intervals (CIs). Results: A total of 11 study were included. Meta-analysis indicated that periodontal disease significantly increased the risk of breast cancer by 1.22-fold (RR = 1.22, 95% CI = 1.06-1.40). Amongst participants with periodontal patients and a history of periodontal therapy, the risk of developing breast cancer was not significant (RR = 1.23; 95% CI = 0.95-1.60). The association results between periodontal diseases and breast cancer were found to be robust, as evident in the leave-one-out sensitivity analysis. Conclusions: Periodontal disease may be a potential risk factor for the development of breast cancer among women, and thus effective periodontal therapy may present as a valuable preventive measure against breast cancer.

Tongue Coating Microbiota Community and Risk Effect on Gastric Cancer

Background: Although oral hygiene and health have long been reported to be associated with increased risk of gastric cancer (GC), the direct relationship of oral microbes with the risk of GC have not been evaluated fully. We aimed to test whether tongue coating microbiome was associated with GC risk. Methods: Pyrosequencing of 16S rRNA gene of tongue coating microbiome was used in 57 newly diagnosed gastric adenocarcinomas and 80 healthy controls. Benjamini-Hochberg (BH) was applied for multiple comparison correction. Co-abundance group (CAGs) analysis was adopted. Results: We found that higher relative abundance of Firmicutes, and lower of Bacteroidetes were associated with increased risk of GC. In genus level, Streptococcus trended with a higher risk of GC, the four other genera (Neisseria, Prevotella, Prevotella7, and Porphyromonas) were found to have a decreased risk of GC. Different from overall GC and non-cardia cancer, Alloprevotella and Veillonella trended with the higher risk of cardia cancer. Finally, we analyzed the microbiota by determining CAGs and six clusters were identified. Except the Cluster 2 (mainly Streptococcus and Abiotrophia), the other clusters had an inverse association with GC. Of them, the Cluster 6 (mainly Prevotella and Prevotella7 etc) had a relatively good classification power with 0.76 of AUC. Conclusion: Microbiome in tongue coating may have potential guiding value for early detection and prevention of GC.

Periodontal Disease and Risk of Bladder Cancer: A Meta-Analysis of 298476 Participants

Objective: It has been reported that the periodontal disease is linked to a number of malignant tumors such as lung cancer and pancreatic cancer. In this study, we aimed to investigate the association of periodontal disease with risk of bladder cancer by a meta-analysis.

Methods: PubMed, Scopus, ScienceDirect, and Chinese National Knowledge Infrastructure (CNKI) were searched for eligible publications up to December 15, 2017. Cohort and nested case-control studies on the association between periodontal disease and risk of bladder cancer were included. After study selection and data extraction, pooled hazard ratios (HRs) and their 95% confidence intervals (95%CIs) were calculated using a fixed-effect inverse-variance model. All analyses were performed using the RevMan 5.3 software.

Results: Finally, five cohort studies were identified and included in this meta-analysis, involving 1,104 bladder cancer cases of 298,476 participants. Summary estimates based on adjusted data showed that periodontal disease was not significantly associated with the risk of bladder cancer (HR = 1.09, 95% CI = 0.95–1.25, I² = 0%). A similar result was also observed after cumulative, subgroup and sensitivity analyses.

Conclusions: Current evidence from cohort studies suggests that patients with periodontal disease may not be at an increased risk of developing bladder cancer.

Mucosal microbiome dysbiosis in gastric carcinogenesis

OBJECTIVES

We aimed to characterise the microbial changes associated with histological stages of gastric tumourigenesis.

DESIGN

We performed 16S rRNA gene analysis of gastric mucosal samples from 81 cases including superficial gastritis (SG), atrophic gastritis (AG), intestinal metaplasia (IM) and gastric cancer (GC) from Xi'an, China, to determine mucosal microbiome dysbiosis across stages of GC. We validated the results in mucosal samples of 126 cases from Inner Mongolia, China.

RESULTS

We observed significant mucosa microbial dysbiosis in IM and GC subjects, with significant enrichment of 21 and depletion of 10 bacterial taxa in GC compared with SG (q<0.05). Microbial network analysis showed increasing correlation strengths among them with disease progression (p<0.001). Five GC-enriched bacterial taxa whose species identifications correspond to Peptostreptococcus stomatis, Streptococcus anginosus, Parvimonas micra, Slackia exigua and Dialister pneumosintes had significant centralities in the GC ecological network (p<0.05) and classified GC from SG with an area under the receiver-operating curve (AUC) of 0.82. Moreover, stronger interactions among gastric microbes were observed in Helicobacter pylori-negative samples compared with H. pylori-positive samples in SG and IM. The fold changes of selected bacteria, and strengths of their interactions were successfully validated in the Inner Mongolian cohort, in which the five bacterial markers distinguished GC from SG with an AUC of 0.81.

CONCLUSIONS

In addition to microbial compositional changes, we identified differences in bacterial interactions across stages of gastric carcinogenesis. The significant enrichments and network centralities suggest potentially important roles of P. stomatis, D. pneumosintes, S. exigua, P. micra and S. anginosus in GC progression.

Periodontal Disease, Tooth Loss, and Cancer Risk

Periodontal disease, which includes gingivitis and periodontitis, is highly prevalent in adults and disease severity increases with age. The relationship between periodontal disease and oral cancer has been examined for several decades, but there is increasing interest in the link between periodontal disease and overall cancer risk, with systemic inflammation serving as the main focus for biological plausibility. Numerous case-control studies have addressed the role of oral health in head and neck cancer, and several cohort studies have examined associations with other types of cancers over the past decade. For this review, we included studies that were identified from either 11 published reviews on this topic or an updated literature search on PubMed (between 2011 and July 2016). A total of 50 studies from 46 publications were included in this review. Meta-analyses were conducted on cohort and case-control studies separately when at least 4 studies could be included to determine summary estimates of the risk of cancer in relation to 1) periodontal disease or 2) tooth number (a surrogate marker of periodontal disease) with adjustment for smoking. Existing data provide support for a positive association between periodontal disease and risk of oral, lung, and pancreatic cancers; however, additional prospective studies are needed to better inform on the strength of these associations and to determine whether other cancers are associated with periodontal disease. Future studies should include sufficiently large sample sizes, improved measurements for periodontal disease, and thorough adjustment for smoking and other risk factors.

Association between tooth loss and risk of oesophageal cancer: a dose-response meta-analysis

Many epidemiological studies have found that tooth loss is associated with susceptibility to oesophageal cancer. However, a definitive answer is yet to be discovered, and the findings are inconclusive. We performed a meta-analysis to assess the relationship between tooth loss and oesophageal cancer risk. We searched PubMed and Embase databases to screen eligible studies up to June 2015. Nine observational studies (eight articles) involving 2604 patients and 113,995 participants were included in the meta-analysis. The combined odds ratio for tooth loss and oesophageal cancer was 1.53 (95 % CI 1.02-2.29) for the high versus lowest teeth loss categories. However, inconsistent results were detected in the stratified and sensitivity analysis. In dose-response analysis, the summary odds ratio for each one tooth loss increment was 1.01 (95 % CI 1.00-1.02). The current evidence, based solely on six case-control studies and three cohort studies, suggests that tooth loss is a potential marker of oesophageal cancer. However, no firm conclusion can be drawn at this time that tooth loss may play a causal role in development of oesophageal cancer. Additional large-scale and high-quality prospective studies are required to evaluate the association between tooth loss and risk of oesophageal cancer.