Gastric atrophy and oesophageal squamous cell carcinoma: possible interaction with dental health and oral hygiene habit

Chronic atrophic gastritis and risk of incident upper gastrointestinal cancers: a systematic review and meta-analysis

BACKGROUND

Previous literature has explored the relationship between chronic atrophic gastritis (CAG) and isolated cancers within the upper gastrointestinal cancers; However, an integrative synthesis across the totality of upper gastrointestinal cancers was conspicuously absent. The research objective was to assess the relationship between CAG and the risk of incident upper gastrointestinal cancers, specifically including gastric cancer, oesophageal cancer, and oesophagogastric junction cancer.

METHODS

Rigorous systematic searches were conducted across three major databases, namely PubMed, Embase and Web of Science, encompassing the timeline from database inception until August 10, 2023. We extracted the necessary odds ratio (OR) and their corresponding 95% confidence interval (CI) for subsequent meta-analysis. Statistical analyses were conducted using Stata 17.0 software.

RESULTS

This meta-analysis included a total of 23 articles encompassing 5858 patients diagnosed with upper gastrointestinal cancers. CAG resulted in a statistically significant 4.12-fold elevated risk of incident gastric cancer (OR = 4.12, 95% CI 3.20-5.30). Likewise, CAG was linked to a 2.08-fold increased risk of incident oesophageal cancer (OR = 2.08, 95%CI 1.60-2.72). Intriguingly, a specific correlation was found between CAG and the risk of incident oesophageal squamous cell carcinoma (OR = 2.29, 95%CI 1.77-2.95), while no significant association was detected for oesophageal adenocarcinoma (OR = 0.62, 95%CI 0.17-2.26). Moreover, CAG was correlated with a 2.77-fold heightened risk of oesophagogastric junction cancer (OR = 2.77, 95%CI 2.21-3.46). Notably, for the same type of upper gastrointestinal cancer, it was observed that diagnosing CAG through histological methods was linked to a 33-77% higher risk of developing cancer compared to diagnosing CAG through serological methods.

CONCLUSION

This meta-analysis indicated a two- to fourfold increased risk of gastric cancer, oesophageal cancer, and oesophagogastric junction cancer in patients with CAG. Importantly, for the same upper gastrointestinal cancer, the risk of incident cancer was higher when CAG was diagnosed histologically compared to serological diagnosis. Further rigorous study designs are required to explore the impact of CAG diagnosed through both diagnostic methods on the risk of upper gastrointestinal cancers.

Upper gastrointestinal tract microbiota with oral origin in relation to oesophageal squamous cell carcinoma

Introduction: Poor oral hygiene is linked to high risks of many systemic diseases, including cancers. Oral dysbiosis is closely associated with poor oral hygiene, causing tooth loss, gingivitis, and periodontitis. We provide a summary of studies and discuss the risk factors for oesophageal squamous cell carcinoma (ESCC) from a microbial perspective in this review.Methods: A literature search of studies published before December 31, 2022 from PubMed, Web of Science, and The Cochrane Library was performed. The search strategies included the following keywords: (1) oral care, oral health, oral hygiene, dental health, dental hygiene, tooth loss, teeth loss, tooth absence, missing teeth, edentulism, tooth brushing, mouthwash, and tooth cleaning; (2) esophageal, esophagus, oesophagus, and oesophageal; (3) cancer, carcinoma, tumor, and neoplasm.Discussion: Poor oral health, indicated by infrequent tooth brushing, chronic periodontitis, and tooth loss, has been associated with an increased risk of squamous dysplasia and ESCC. Oral microbial diversity and composition are profoundly dysregulated during oesophageal tumorigenesis. Similar to the oral microbiota, the oesophageal microbiota varies distinctly in multiple bacterial taxa in ESCC and gastric cardia adenocarcinoma, both of which have high co-occurrence rates in the "Oesophageal Cancer Belt". In addition, the potential roles of oncogenic viruses in ESCC have also been discussed. We also briefly explore the potential mechanisms underlying the tumor-promoting role of dysregulated microbiota for the development of therapeutic targeting strategies.Conclusion: Poor oral health is an established risk indicator of ESCC. The dysbiosis of microbiota in upper gastrointestinal tract that highly resembles the oral microbial ecosystem but with distinct features at individual sites contributes to the development and progression of ESCC.

Current Status and Future Prospects for Esophageal Cancer

Esophageal cancer (EC) is the ninth most common cancer and the sixth leading cause of cancer deaths worldwide. Esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC) are the two main histological subtypes with distinct epidemiological and clinical features. While the global incidence of ESCC is declining, the incidence of EAC is increasing in many countries. Decades of epidemiologic research have identified distinct environmental exposures for ESCC and EAC subtypes. Recent advances in understanding the genomic aspects of EC have advanced our understanding of EC causes and led to using specific genomic alterations in EC tumors as biomarkers for early diagnosis, treatment, and prognosis of this cancer. Nevertheless, the prognosis of EC is still poor, with a five-year survival rate of less than 20%. Currently, there are significant challenges for early detection and secondary prevention for both ESCC and EAC subtypes, but Cytosponge™ is shifting this position for EAC. Primary prevention remains the preferred strategy for reducing the global burden of EC. In this review, we will summarize recent advances, current status, and future prospects of the studies related to epidemiology, time trends, environmental risk factors, prevention, early diagnosis, and treatment for both EC subtypes.

Association of Serum Pepsinogens With Esophageal Squamous Cell Carcinoma Risk: A Systematic Review and Meta-Analysis

Background

Serum pepsinogens are serological biomarkers of gastric atrophy, and the latter is a risk factor for esophageal squamous cell carcinoma (ESCC). However, the association of serum pepsinogens with ESCC risk remains unclear. This systematic review and meta-analysis aimed to assess the relationship between serum pepsinogen I (PGI) and pepsinogen I: pepsinogen II ratio (PGR) and ESCC risk.

Methods

PubMed, Embase, and Web of Science were searched for articles on the effect of serum PGI and PGR on ESCC risk, published up to the end of February 2022. Meta-analysis with a random-effect model was used to calculate pooled odds ratios (ORs) and 95% confidence intervals (CIs).

Results

Five case–control studies and three prospective studies were included. In comparison with the high categories, the low categories of serum PGI (OR: 1.92, 95% CI: 1.45–2.56) and PGR (OR: 1.70, 95% CI: 1.01–2.85) were associated with an increased risk of ESCC, although a substantial heterogeneity was observed in serum PGR (I² = 60.2%, P = 0.028) rather than in serum PGI (I² = 46.4%, P = 0.070). In stratified analysis by study quality, the significant risk effect on ESCC was remained for PGI (OR: 2.05, 95% CI: 1.48–2.84) and PGR (OR: 2.07, 95% CI: 1.17–3.75) when only the studies with high quality were pooled.

Conclusions

Based on the available studies, although limited in number, this systematic review along with meta-analysis suggests that low serum PGI and low PGR may be related to an increased risk of ESCC. This present study provides evidence for using serum pepsinogen biomarkers in predicting ESCC. More delicate well-designed cohort studies with high study quality are needed, and dose–response analysis should be performed.

Association between the frequency of tooth brushing and esophageal carcinoma risk: an update systematic review and meta-analysis

Background

Lower frequency of tooth brushing was thought to be associated with esophageal carcinoma (EC). However, some researchers suggested that this association did not exist or had not yet reached statistical significance. The purpose of this study was to calculate a more precise estimation of the relationship between the frequency of tooth brushing and the risk of EC by combining the results between different studies using the meta-analysis.

Methods

We searched the PubMed, Embase, Web of Science, and Scopus electronic databases up to July 2021. According to PECO approach (Population, Exposure, Comparator and Outcomes), we assessed the association between tooth brushing frequency and EC risk which reported the adjusted risk ratios (adjRR), hazard ratios (adjHR), or odds ratios (adjOR) with 95% confidence interval (CI). The random effects model was used to quantitatively evaluate the combined results. Two researchers independently evaluated the risk bias of the included studies using the Newcastle-Ottawa Scale (NOS). The robustness of results was evaluated by subgroup analysis, sensitivity analysis, and publication bias.

Results

In total, we identified 13 articles with 14 case-control studies which included 16,773 participants and 5,673 patients. Pooled results showed the lowest frequency of brushing was significantly associated with an increased risk of EC in comparison to the highest (adjOR: 2.00, 95% CI: 1.61-2.48). There was moderate heterogeneity among included studies (P=0.001, I2=61.4%). The original studies included in this meta-analysis were all case-control studies. Study quality was all moderate or above based on NOS score ranges of 6 stars or more.

Conclusions

Available evidence suggests a low frequency of tooth brushing may be an important risk factor for EC. However, higher quality studies should continue to be conducted to investigate the optimal threshold of brushing frequency for the prevention of EC.

A long-term follow-up analysis of associations between tooth loss and multiple cancers in the Linxian General Population Cohort

Poor oral health, indicated by tooth loss and periodontal disease, may be an important risk factor for various cancers. Prior studies have found inconsistent associations between tooth loss and several cancer types. Here, we examined the relationship between tooth loss and incident cases of multiple cancers in the Linxian General Population Nutrition Intervention Trial cohort. In this large prospective cohort of over 29,000 participants, there were 3101, 1701, 626, 327, 348, and 179 incident esophageal, gastric cardia, gastric noncardia, liver, lung, and colorectal cancer cases, respectively, over 30 years of follow-up. Adjusted Cox proportional hazards regression models with time-varying covariates were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between tooth loss and cancer outcomes during three time intervals: ≤ 5 years (early), > 5 and ≤ 10 years (mid), > 10 years (late). Tooth loss was assessed as quartiles of the number of lost teeth in excess of the loess smoothed, age-specific median number of teeth lost. For esophageal cancer, the increase in risk associated with the highest quartile of tooth loss was 25% (95% CI: 1.02, 1.52) in the mid time interval, but the association weakened thereafter. For gastric cardia cancer, the increase in risk associated with the highest quartile of tooth loss was 1.34 in both the early (95% CI: 1.06, 1.71) and mid time intervals (95% CI: 1.02, 1.76), with no significant associations in the late interval. Gastric noncardia cancer was only associated with the second quartile of tooth loss in the late time interval (HR = 1.54; 95% CI: 1.16, 2.04). All associations between tooth loss and liver, lung, and colorectal cancers were null. Tooth loss was associated with risk of esophageal and gastric cancers in this updated analysis from the cohort.

Association of Helicobacter pylori and gastric atrophy with adenocarcinoma of the esophagogastric junction in Taixing, China

Gastric atrophy caused by Helicobacter pylori infection was suggested to influence the risk of adenocarcinoma of the esophagogastric junction (AEGJ), however, the evidence remains limited. We aimed to examine the associations of H. pylori infection and gastric atrophy (defined using serum pepsinogen [PG] I to PGII ratio) with AEGJ risk, based on a population-based case-control study in Taixing, China (2010-2014), with 349 histopathologically confirmed AEGJ cases and 1859 controls. We explored the potential effect modification by H. pylori serostatus and sex on the association of serum PGs with AEGJ risk. We used unconditional logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals (CIs). H. pylori seropositivity was associated with an elevated AEGJ risk (OR = 1.95, 95% CI: 1.47-2.63). Neither CagA-positive nor VacA-positive strains dramatically changed this association. Gastric atrophy (PGI/PGII ratio ≤4) was positively associated with AEGJ risk (OR = 2.36, 95% CI: 1.72-3.22). The fully adjusted ORs for AEGJ progressively increased with the increasing levels of PGII (P-trend <.001). H. pylori showed nonsignificant effect modification (P-interaction = .385) on the association of gastric atrophy with AEGJ. In conclusion, H. pylori and gastric atrophy were positively associated with AEGJ risk. These results may contribute evidence to the ongoing research on gastric atrophy-related cancers and guide the prevention and control of AEGJ.

Oral Health and Risk of Upper Gastrointestinal Cancers in a Large Prospective Study from a High-risk Region: Golestan Cohort Study

Tooth loss and periodontal disease have been associated with several cancers, and poor oral health may be an important risk factor for upper gastrointestinal (UGI, i.e., esophageal and gastric) cancers. We assessed the relationship between oral health and UGI cancers using a large prospective study of over 50,000 adults living in Golestan Province, Iran, a high-incidence area for these cancers. Hazard ratios (HRs) and 95% confidence intervals (CI) were estimated for the association between three different measures of oral health [frequency of tooth brushing; number of missing teeth; and the sum of decayed, missing, and filled teeth (DMFT)] and UGI cancers. During a median follow-up duration of 13 years, there were 794 incident UGI cancers (396 esophageal and 398 gastric cancers). Daily tooth brushing was associated with a decreased risk of developing both esophageal (HR = 0.670; 95% CI: 0.486-0.924) and gastric (HR = 0.741; 95% CI: 0.544-1.01) cancers (combined UGI cancer HR = 0.697; 95% CI: 0.558-0.871) compared with never brushing. Tooth loss in excess of the loess smoothed, age- and sex-specific median number of teeth lost was significantly associated with esophageal (HR = 1.64; 95% CI: 1.08-2.47) and gastric cancers (HR = 1.58; 95% CI: 1.05-2.38). There were some adverse associations between DMFT and UGI cancers but most were not statistically significant. These results suggest increased risk of developing UGI cancers among individuals with poor oral health, and those who do not perform regular oral hygiene. PREVENTION RELEVANCE: Poor oral health is associated with the risk of upper gastrointestinal cancers, and oral hygiene practices may help prevent these cancers.

Risk factors for esophageal iodine-unstained lesions and changing trends among Japanese alcohol-dependent men (2003-2018)

Globally, a decreasing incidence of male esophageal squamous cell carcinoma (ESCC) has been observed in recent decades. We evaluated the determinants of esophageal distinct iodine-unstained lesions (DIULs), high-cancer-risk lesions and ESCC, among 3858 Japanese alcohol-dependent men (40-79 years) who underwent chromoendoscopic screening between 2003 and 2018. The initial screening detected DIULs ≥ 5 mm in 541 patients (dysplasia in 319 and SCC in 129) and multiple DIULs in 640. The detection rates for DIULs and chronic atrophic gastritis (CAG), pack-years, and the mean corpuscular volume (MCV) decreased over the course of the study period, while the detection of hiatal hernia and/or columnar-lined esophagus (HH/CLE) and the carriers of inactive heterozygous aldehyde dehydrogenase-2 (ALDH2, rs671) increased. Multiple logistic regression analyses showed that an older age, larger number of pack-years, smaller body mass index, larger MCV, presence of a slow-metabolizing alcohol dehydrogenase-1B genotype (rs1229984), presence of an inactive heterozygous ALDH2 genotype, and more advanced degree of CAG increased the odds ratios (ORs) for DIULs, while the 2008-2013 and 2014-2018 screening periods had lower ORs for DIULs than the 2003-2007 screening period. The presence of HH/CLE decreased the OR for multiple DIULs and was associated with a more proximal location of ESCC. In conclusion, the detection of DIULs in an alcohol-dependent population decreased between 2003 and 2018. In addition to reported determinants of ESCC, CAG and HH/CLE were associated with the risk of DIULs. Enigmatically, however, the decline in the detection of DIULs was not adequately explained by these factors and warrants further research.

Urinary exposure of N-nitrosamines and associated risk of esophageal cancer in a high incidence area in China

Esophageal cancer (EC) is a deadly malignancy worldwide with a high incidence and exhibits unevenly geographic prevalence, which suggests that environmental factors are deeply involved in the development of EC. Although the carcinogenesis of nitrosamines in the esophagus has been identified by tremendous toxicological data, the role of nitrosamines in the genesis of human EC has so far proved inconclusive largely due to a lack of convincing evidences. In this study, urinary nitrosamines in population controls and cases with esophageal precancerous lesions, including reflux esophagitis (RE) accompanying with basal cell hyperplasia (BCH) and dysplasia (DYS), and esophageal squamous cell carcinoma (ESCC) were detected by a SPE-LC-MS/MS method and the associated risk was evaluated. Higher excretion concentrations of N-nitrosomethylethylamine (NMEA) in the RE/BCH patients, NMEA and N-nitrosodibutylamine (NDBA) in the DYS patients, and NMEA, NDBA, N-nitrosopyrrolidine (NPyr) and N-nitrosomorpholine (NMor) in the ESCC patients were observed compared with the controls (p < .05). And with the progression of esophageal lesion, the exposure complexity increased in terms of the categories of nitrosamines. Furthermore, the observed positive associations between the hazardous exposure of NMEA, NDBA and NPyr and the increased risk of ESCC, and between NMEA and NDBA and RE/BCH were established. These findings provided direct evidence to support the hypothesis that exposure to nitrosamines are involved in the carcinogenesis of esophageal epithelia in this high incidence area from the perspective of endogenous exposure assessment. However, discoveries in this study need to be confirmed by systematic researches in the future. And the dose-response relationships, the reference ranges or cutoff values to predict the risks of nitrosamines exposure also need to be defined.

Associations Between Gastric Atrophy and Its Interaction With Poor Oral Health and the Risk for Esophageal Squamous Cell Carcinoma in a High-Risk Region of China: A Population-Based Case-Control Study

Previous findings concerning gastric atrophy as a potential risk factor for esophageal squamous cell carcinoma (ESCC) have been inconsistent. We aimed to test whether gastric atrophy and, further, its interaction with poor oral health elevated the risk of ESCC in a high-risk region of China. Our population-based case-control study in Taixing, China (2010–2014), recruited cases from local hospitals and the local cancer registry. Controls were selected randomly from the local population registry. Ultimately, 1,210 cases and 1,978 controls answered questionnaires and provided blood samples for assay of pepsinogens. Unconditional logistic regression models were used to estimate odds ratios and 95% confidence intervals. Gastric atrophy (defined as a serum level of pepsinogen I of <55 μg/L) was associated with an increased risk for ESCC (odds ratio = 1.61; 95% confidence interval: 1.33, 1.96), even after full adjustment for potential confounding factors. In addition, suggestion of an additive interaction between gastric atrophy and poor oral health was observed (relative excess risk due to interaction = 1.28, 95% confidence interval: 0.39, 2.18). We conclude that gastric atrophy appears to be a risk factor for ESCC in a high-risk region of China, and there is a suggested additive interaction with poor oral health that increases this risk even further.

Polycyclic aromatic hydrocarbons (PAHs) and esophageal carcinoma in Handan-Xingtai district, North China: a preliminary study based on cancer risk assessment

Extremely high risk of esophageal carcinoma (EC) occurs in Handan-Xingtai district of North China. In spite of various preventive measures and epidemiological investigations that have been conducted for years, incidence and mortality of EC are still in the highest level of China. The etiology of EC remains unclear in the region. Previous studies of our research group proposed that polycyclic aromatic hydrocarbons (PAHs) that derived from numerous coal gangue dumps and atmospheric particulates were major contaminants in these regions. In consideration of mutagenic, teratogenic, and carcinogenic characteristics of PAHs, the authors hypothesized that severe exposure to PAHs could preform as a causative factor for EC. Therefore, four data sets documented in our previous studies were employed in this paper. To quantitatively evaluate the carcinogenic risk imposed by sixteen priority PAHs, incremental lifetime cancer risks (ILCRs) via three exposure pathways were calculated. The results showed that total ILCRs for adult group ranged from 2.08E-05 to 8.63E-02, with an average of 2.00E-02. Total ILCRs for childhood group ranged from 1.09E-05 to 4.48E-02, with an average of 1.04E-02. Total ILCR value of 94% samples exceeded 10^-4, indicating a particularly high carcinogenic risk to local residents. Furthermore, ingestion and dermal contact conducted as principal pathways of exposing to PAHs for each population group, rather than inhalation. It can be speculated that severely exposing to PAHs may be a pathogenesis of EC in Handan-Xingtai district. The rigorous supervise and governance are imperative to avoid severe exposure to PAHs that derived from coal gangue dumps.

The profile of Rafsanjan Cohort Study

Owning the largest human-made jungle of pistachio, the second largest copper mine, and being located on the trade route of opium transit, distinguish Rafsanjan from many other cities in Iran. The environmental exposures and lifestyle factors associated with these characteristics of Rafsanjan, have raised concern about possible health outcomes for individuals living in and around this city. Thus, local health authorities initiated the Rafsanjan Cohort Study (RCS), as part of the prospective epidemiological research studies in IrAN (PERSIAN). RCS is a population-based prospective cohort of men and women aged 35-70 years, launched in August 2015. Individuals from diverse socioeconomic levels and lifestyles were recruited from four urban and suburban areas of Rafsanjan (participation rate 67.42%). Questionnaire-based interviews regarding demographics, dietary and environmental exposures, medical and occupational history, as well as anthropometric measurements were completed for all participants. Additionally, bio-specimens (blood, urine, hair, and nail) were collected, and dental and eye examinations were performed. The enrollment phase ended in December 2017, and a 15-year follow-up is planned. A total of 9990 individuals were enrolled in RCS (53.41% females). About 26% of men are pistachio farmers. The baseline prevalence of major non-communicable disease (NCD) risk factors such as cigarette smoking, alcohol consumption and opium use were 25.45%, 10.02%, and 23.81%, respectively. The mean ± SD of other common risk factors are as follows: body mass index (27.83 ± 4.89 mm Hg), systolic blood pressure (107.18 ± 17.56 mm Hg) diastolic blood pressure (71.13 ± 10.83), fasting blood sugar (113.27 ± 39.11 mg/dL) and plasma cholesterol (198.78 ± 41.89 mg/dL). These results indicate a concerning prevalence of NCD risk factors in Rafsanjan city, warranting further detailed investigations, particularly regarding the association of NDC with agricultural/industrial pollutants and drug abuse.

Serum pepsinogen assay is not recommended for the diagnosis of esophageal squamous cell carcinoma: a systematic review and meta-analysis

Background: Serum pepsinogen I (PGI) concentration and PGI/PGII ratio (PGR) are often used as serological markers for gastric fundus atrophy (AGA) and gastric carcinoma. However, their diagnostic value in esophageal carcinoma (EC) is inaccurate. Methods: This study evaluated the diagnostic value of PGI and PGR in EC by searching the PubMed, Web of Science, Embase, Cochrane Library and Cochrane Central Register of Controlled Trials databases for literature on the diagnosis of EC with PGI and PGR from January 1, 2000 to October 2, 2018. The included literature were systematically evaluated using QUSDAS-2 software. Meta-analysis was conducted using STATA 15.0 software. The summary receiver operating characteristic curve (SROC) accuracy was plotted, the area under the curve was calculated. Results: A total of 84 papers were selected, and after screening, nine papers on esophageal squamous cell carcinoma (ESCC) were finally included. Results showed low an ESCC-specific diagnostic sensitivity (0.27), high specificity (0.85), and 0.63 AUC of SROC when PGI≤70 ng/mL. When PGR≤3, the ESCC-specific diagnostic sensitivity was low (0.29), the specificity was high (0.83), and the AUC of SROC was 0.63. Conclusion: According to the current research results, PGI≤70 ng/mL or PGR≤3 diagnostic ESCC sensitivity is low, and specificity is high. These findings indicate that neither PGI≤70 ng/mL nor PGR≤3 can be used as an ESCC-screening index.

Systematic review: the etiology of esophageal squamous cell carcinoma in low-income settings

Esophageal carcinoma causes over 380 000 deaths per year, ranking sixth worldwide in mortality amongst all malignancies. Globally, the squamous cell subtype is most common and accounts for 80% of esophageal cancers. Nonetheless, esophageal squamous cell carcinoma is much more poorly understood than esophageal adenocarcinoma, including what is driving such high prevalences, why it often presents in young patients, and shows such marked geographical delineations Areas covered: The current literature was searched for articles focusing on aetiopathogenesis of squamous cell esophageal carcinoma via a systematic review, particularly in low-resource settings. This was supplemented by papers of interest known to the authors. Expert commentary: Current putative mechanisms include polycyclic aromatic hydrocarbons, nitrosamines, acetaldehyde, cyclo-oxygenase-2 pathways, androgen and their receptor levels, as well as smoking & alcohol, micronutrient deficiencies and diet, mycotoxins, thermal damage, oral hygiene and microbiotal factors, inhaled smoke, viral infections such as HPV, and chronic irritative states. Etiology is likely multifactorial and varies geographically. Though smoking and alcohol play a predominant role in high-income settings, there is strong evidence that mycotoxins, diet and temperature effects may play an under-recognized role in low and middle-income settings.

[Research progress on the relationship between oral microbes and digestive system diseases]

The human microbiome project promoted further understanding on human oral microbes. Besides oral diseases such as dental caries, periodontal disease, and oral cancer, oral microbes are closely associated with systematic diseases. They have a close connection with digestive system diseases and even contribute to the origination and progression of colorectal cancer. By reviewing recent studies involving oral microbe-related digestive systemic diseases, we aim to propose the considerable role of oral microbes in relation to digestive systemic diseases and the way of oral microbes to multiple organs of digestive system.

Oral health and mortality in the Golestan Cohort Study

Background

Previous studies have found associations between oral health and mortality, but the majority of previous studies have been conducted in high-income countries.

Methods

We used data from the Golestan Cohort Study, a study of 50 045 people aged 40 to 75 years in north eastern Iran, recruited from January 2004 to June 2008. Tooth loss and decayed, missing and filled teeth (DMFT) were assessed by trained physicians. Frequency of tooth brushing and use of dentures were self-reported. Cause-specific mortality was ascertained through March 2014. We calculated hazard ratios (HRs) and 95% confidence intervals (95% CIs) for the associations between the oral health variables, overall mortality and cause-specific mortality.

Results

Participants with the greatest tooth loss had increased overall mortality (HR 1.43; 95% CI: 1.28, 1.61) compared with those with the least tooth loss; similar estimates were observed for DMFT score. For cause-specific mortality, an increased risk of death was found for tooth loss and mortality from cardiovascular disease (HR 1.33; 95% CI: 1.13, 1.56), cancer (HR 1.30; 95% CI: 1.03, 1.65) and injuries (HR 1.99; 95% CI: 1.28, 3.09). The associations between oral health and injury mortality were strongly attenuated after exclusion of participants with comorbid conditions at baseline. No statistical interaction was found between denture use and tooth loss or DMFT on mortality.

Conclusions

Poor oral health appears to predict overall and cause-specific mortality in populations in economic transition. Investigation of the underlying mechanisms might provide an important contribution to reducing mortality.

Poor oral health is associated with an increased risk of esophageal squamous cell carcinoma - a population-based case-control study in China

To further examine the association between oral hygiene and esophageal squamous cell carcinoma (ESCC) risk and the effect modification of other exposures, we conducted a population-based case-control study between 2010 and 2012 in Taixing, China, a high-risk area for ESCC. Cases were primarily recruited from endoscopy units at local hospitals, supplemented by linkage to the local Cancer Registry. Control subjects were frequency matched to cases by sex and age (5-year groups) and were randomly selected from the Taixing Population Registry. For the current analysis, data from 616 histopathologically confirmed cases and 770 controls with complete information on oral hygiene were analyzed. Unconditional logistic regression models, including oral hygiene indicators and potential behavioral confounders, were used to derive odds ratios (ORs) and 95% confidence intervals (CIs). Tooth loss was only marginally significantly associated with ESCC risk (yes vs. no, OR = 1.29, 95% CI 0.94-1.74). However, the excess risk increased with increasing numbers of lost teeth (more than 6 teeth lost vs. none, OR = 1.48, 95% CI 1.04-2.11). Tooth brushing once or less per day, compared with tooth brushing twice or more per day, was associated with a 1.81-fold increased risk of ESCC. In the stratification analyses, the increased risks associated with these indicators of oral health were more pronounced in older subjects (age ≥ 70 years), women, non-smokers, and non-drinkers. Further studies are warranted to verify these findings and to explore the underlying mechanisms, e.g., changed oral microbiota, associated with poor oral hygiene.

Esophageal Cancer in Golestan Province, Iran: A Review of Genetic Susceptibility and Environmental Risk Factors

Esophageal squamous cell carcinoma (ESCC) is an aggressive tumor that is typically diagnosed only when the tumor has gained remarkable size, extended to peripheral tissues, and led to dysphagia. Five-year survival of advanced cancer is still very poor (19%), even with improved surgical techniques and adjuvant chemoradiation therapy. Therefore, early detection and prevention are the most important strategies to reduce the burden of ESCC. Our review will focus on the studies conducted in Golestan province, an area with a high prevalence of ESCC in northern Iran. We review three aspects of the research literature on ESCC: epidemiological features, environmental factors (including substance abuse, environmental contaminants, dietary factors, and human papillomavirus [HPV]), and molecular factors (including oncogenes, tumor suppressor genes, cell cycle regulatory proteins, and other relevant biomarkers). Epidemiological and experimental data suggest that some chemicals and lifestyle factors, including polycyclic aromatic hydrocarbons (PAHs), cigarette smoking, opium use, and hot tea drinking are associated with the development of ESCC in Golestan. HPV infects the esophageal epithelium, but so far, no firm evidence of its involvement in esophageal carcinogenesis has been provided. Some of these factors, notably hot tea drinking, may render the esophageal mucosa more susceptible to injury by other carcinogens. There are few studies at molecular level on ESCC in Golestan. Increasing awareness about the known risk factors of ESCC could potentially reduce the burden of ESCC in the region. Further studies on risk factors, identifying high risk populations, and early detection are needed.

Oral Hygiene and Risk of Nasopharyngeal Carcinoma-A Population-Based Case-Control Study in China

BACKGROUND

The association between oral health and risk of nasopharyngeal carcinoma (NPC) is largely unknown. Further understanding could shed light on potential pathogenic mechanisms and preventive measures.

METHODS

We conducted a population-based case-control study in southern China between 2010 and 2014. We enrolled 2,528 incident NPC cases, aged 20-74 years, and 2,596 controls, randomly selected from the total population registers, with frequency matching to the 5-year age and sex distribution of the cases by geographic region. We interviewed subjects using a structured questionnaire inquiring about oral health indicators and potential confounding factors. We used unconditional logistic regression to estimate multivariate-adjusted ORs with 95% confidence intervals (CI).

RESULTS

A higher number of filled teeth was associated with an elevated risk of NPC. Individuals with 1 to 3 and more than 3 teeth filled versus none had adjusted ORs of 1.25 (95% CI, 1.06-1.49) and 1.55 (95% CI, 1.13-2.12), respectively (Ptrend = 0.002). Conversely, the adjusted OR for those who brushed teeth twice or more per day versus once or less per day was 0.62 (95% CI, 0.55-0.70). We detected a borderline significant positive association with earlier age at first adult tooth loss.

CONCLUSION

Our study suggested a positive association between some indicators of poor oral health and risk of NPC. Further studies are needed to confirm whether the findings are causal and, if so, to further explain the underlying mechanisms.

IMPACT

Improvement of oral hygiene might contribute to reducing NPC risk. Cancer Epidemiol Biomarkers Prev; 25(8); 1201-7. ©2016 AACR.

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

Observational studies showed that tooth loss is associated with gastric cancer, but the findings are inconsistent. In this study, a meta-analysis was conducted to evaluate the relationship between tooth loss and gastric cancer. Relevant studies were screened in PubMed and Embase databases, and nine observational studies were considered eligible for the analysis. The combined relative risks for the highest versus the lowest categories of tooth loss were 1.86 (95% CI: 1.08–3.21) and 1.31 (95% CI: 1.12–1.53) in case control and cohort studies, respectively. However, unstable results were observed in the stratified and sensitivity analysis. The current evidence, based solely on four case-control studies and five cohort studies, suggested that tooth loss is a potential marker of gastric cancer. However, we can not concluded at this time that tooth loss may be a risk factor for gastric cancer due to significant heterogeneity among studies and mixed results between case-control studies and cohort studies. Additional large-scale and high-quality prospective studies are required to evaluate the association between tooth loss and risk of gastric cancer.

Oral Microbiota and Risk for Esophageal Squamous Cell Carcinoma in a High-Risk Area of China

Poor oral health has been linked with an increased risk of esophageal squamous cell carcinoma (ESCC). We investigated whether alteration of oral microbiota is associated with ESCC risk. Fasting saliva samples were collected from 87 incident and histopathologicallly diagnosed ESCC cases, 63 subjects with dysplasia and 85 healthy controls. All subjects were also interviewed with a questionnaire. V3-V4 region of 16S rRNA was amplified and sequenced by 454-pyrosequencing platform. Carriage of each genus was compared by means of multivariate-adjusted odds ratios derived from logistic regression model. Relative abundance was compared using Metastats method. Beta diversity was estimated using Unifrac and weighted Unifrac distances. Principal coordinate analysis (PCoA) was applied to ordinate dissimilarity matrices. Multinomial logistic regression was used to compare the coordinates between different groups. ESCC subjects had an overall decreased microbial diversity compared to control and dysplasia subjects (P<0.001). Decreased carriage of genera Lautropia, Bulleidia, Catonella, Corynebacterium, Moryella, Peptococcus and Cardiobacterium were found in ESCC subjects compared to non-ESCC subjects. Multinomial logistic regression analyses on PCoA coordinates also revealed that ESCC subjects had significantly different levels for several coordinates compared to non-ESCC subjects. In conclusion, we observed a correlation between altered salivary bacterial microbiota and ESCC risk. The results of our study on the saliva microbiome are of particular interest as it reflects the shift in microbial communities. Further studies are warranted to verify this finding, and if being verified, to explore the underlying mechanisms.

Variations of gastric corpus microbiota are associated with early esophageal squamous cell carcinoma and squamous dysplasia

Observational studies revealed a relationship between changes in gastric mucosa and risk of esophageal squamous cell carcinoma (ESCC) which suggested a possible role for gastric microbiota in ESCC carcinogenesis. In this study we aimed to compare pattern of gastric corpus microbiota in ESCC with normal esophagus. Cases were included subjects with early ESCC (stage I-II) and esophageal squamous dysplasia (ESD) as the cancer precursor. Control groups included age and sex-matched subjects with mid-esophagus esophagitis (diseased-control), and histologically normal esophagus (healthy-control). DNA was extracted from snap-frozen gastric corpus tissues and 16S rRNA was sequenced on GS-FLX Titanium. After noise removal, an average of 3004 reads per sample was obtained from 93 subjects. We applied principal coordinate analysis to ordinate distances from beta diversity data. Pattern of gastric microbiota using Unifrac (p = 0.004) and weighted Unifrac distances (p = 0.018) statistically varied between cases and healthy controls. Sequences were aligned to SILVA database and Clostridiales and Erysipelotrichales orders were more abundant among cases after controling for multiple testing (p = 0.011). No such difference was observed between mid-esophagitis and healthy controls. This study is the first to show that composition of gastric corpus mucosal microbiota differs in early ESCC and ESD from healthy esophagus.

Oral hygiene status in a general population of Iran, 2011: a key lifestyle marker in relation to common risk factors of non-communicable diseases

BACKGROUND

To estimate Oral Hygiene (OH) status in the Iranian population in 2011, and to determine the influence of socio-economic characteristics on OH, and its interrelation with common risk factors of Non-Communicable Diseases (NCDs).

METHODS

Data including a total of 12,105 individuals aged 6-70 years were obtained from the sixth round of the surveys of NCDs risk factors in Iran. OH was recorded through a structured questionnaire measuring daily frequencies of tooth brushing and dental flossing. Descriptive analyses were performed on demographic characteristics in the complex sample survey setting. We also employed weighted binary logistic regression to compute Odds Ratio (OR) as a measure of association between the response and explanatory factors. Furthermore, to construct an asset index, we utilized Principal Component Analysis (PCA).

RESULTS

The percentage with minimum recommended daily OH practices was 3.7% among men and 7.7% among women (OR= 2.3; P<0.001). Urban citizens were more likely to have their teeth cleaned compared to rural people (OR= 2.8; P<0.001). For both genders, a relatively better condition was observed in the 25-34 age group (male: 5.6%; female: 10.3%). In addition, OH status improved significantly by increase in both level of education (P<0.001) and economic status (P<0.001). There were also apparent associations between self-care practices and specific behavioral risk factors, though the correlation with dietary habits and tobacco use could be largely explained by socio-economic factors.

CONCLUSION

OH situation in Iran calls for urgent need to assign proper interventions and strategies toward raising public awareness and reducing disparities in access to health facilities.

Association of tooth loss and oral hygiene with risk of gastric adenocarcinoma

Poor oral health and tooth loss have been proposed as possible risk factors for some chronic diseases, including gastric cancer. However, a small number of studies have tested these associations. We conducted a case-control study in Golestan Province, Iran, that enrolled 309 cases diagnosed with gastric adenocarcinoma (118 noncardia, 161 cardia, and 30 mixed-locations) and 613 sex, age, and neighborhood matched controls. Data on oral health were obtained through physical examination and questionnaire including tooth loss, the number of decayed, missing, and filled teeth, and frequency of tooth brushing. ORs and 95% confidence intervals (95% CI) were obtained using conditional logistic regression models adjusted for potential confounders. Standard one degree-of-freedom linear trend test and a multiple degree-of-freedom global test of the effect of adding oral hygiene variables to the model were also calculated. Our results showed apparent associations between tooth loss and decayed, missing, filled teeth (DMFT) score with risk of gastric cancer, overall and at each anatomic subsite. However, these associations were not monotonic and were strongly confounded by age. The results also showed that subjects who brushed their teeth less than daily were at significantly higher risk for gastric cardia adenocarcinoma ORs (95% CI) of 5.6 (1.6-19.3). We found evidence for an association between oral health and gastric cancer, but the nonmonotonic association, the relatively strong effect of confounder adjustment, and inconsistent results across studies must temper the strength of any conclusions.