Study On The Association Of Oral Hygiene With Esophageal Carcinoma

Background and ObjectivesEsophageal carcinoma (EC) is the eighth most common incident cancer and the sixth leading cause of cancer death worldwide. EC affects more than 450,000 people worldwide, and respect to prognosis and a fatal outcome in the great majority of cases, EC is considered as a serious malignancy. Squamous cell carcinoma and adenocarcinoma are the commonly seen forms of EC worldwide. Esophageal squamous cell carcinoma (ESCC) is the predominant form in developing countries, whereas a shift in epidemiology has been seen for some developed countries, where the incidence of esophageal adenocarcinoma (EAC) now exceeds that of squamous-cell types.Single factor can not explain the onset of esophageal cancer, generally, the occurrence of EC is believed to be the result of a multi-factor multi-stage development process. Numerous epidemiologic investigations and researches have focused on the epidemiological etiology to explain the rapid increase of this lethal cancer. Tobacco use, alcohol consumption and mutations of enzymes that metabolizing alcohol have been the primary causes of esophageal squamous cell carcinoma (ESCC), however, alcohol consumption is not considered as a risk factor for esophageal adenocarcinoma (EAC). For EAC, symptomatic gastro-esophageal reflux disease, Barrett’s esophagus, obesity are considered as major risk factors. Poor oral health has been associated with increased risk of cancer at several sites (i.e. oral cancer, gastric cancer, head and neck cancer, throat cancer etc.). Therefore, as for teeth loss and the frequency of teeth brushing, the association with EC risk is controversial.Section one "A case-control study of the association between oral hygiene and EC": Taixing City in Eastern China has some of the highest incidence of ESCC. Similar to other high-risk areas, little is known about the etiology of ESCC in this area. Since October 2010, a population-based case-control study was conducted to investigate the association between oral hygiene and EC. Section two "Teeth loss, teeth brushing and esophageal carcinoma:a meta-analysis":Studies have researched on the association between teeth loss and teeth brushing and the risk of EC, but with inconsistent results. This meta-analysis was conducted to access the contributions of teeth brushing and teeth loss to the risk of EC.Materials and Methods1. A population-based case-control study was conducted with newly-diagnosed ESCC patients. Cases were recruited mainly from endoscopy units at local hospitals, and were supplemented by additional linkage to the local Cancer Registry. Control subjects were frequency matched to the cases on sex and age in 5-year groups and randomly selected from the Taixing Population Registry. General information and variables on oral hygiene were collected by the trained investigators. Data analysis was performed using SAS 9.1 software. Unconditional logistic regression models, including terms of oral hygiene indicators and potential behavioral confounders, were used to obtain odds ratios (OR) and 95% confidence intervals (CI).2. A meta-analysis was performed with comprehensive search foe relevant articles. I2 was used to evaluate the heterogeneity among studies. Fixed or random effect pooled measure was selected on the basis of the results of homogeneity test. Subgroup analysis were used to explore potential sources of between-study heterogeneity (case type, study location and study design). An analysis of influence was carried out, which describes how robust the pooled estimator is to removal of individual studies. Publication bias was estimated using Egger’s regression asymmetry test. Data analyses were performed using State (version 13.1; Stata Corporation, College Station, TX,USA) software.All reported probabilities (P-values) were two-sided, and the values less than 0.05 were considered significant.Results1. A total of 616 ESCC patients and 770 age-sex-matched controls were included in this article. The male to female ratio was 2.31:1. Teeth loss was marginally significantly associated with ESCC risk (OR=1.33,95% CI:0.99-1.79), and subjects with more than 6 teeth lost had a higher risk (OR=1.54,95% CI:1.09-2.17) of having ESCC compared with those without tooth loss. Teeth brushing once per day or less often, compared with tooth brushing twice or more, was associated with a 1.95-fold increased risk of ESCC. In stratification analysis, this increased risk associated with these indicators of oral health was more pronounced among women, non-smokers, non-drinkers or older subjects (ages ≥70).2. Eleven articles with thirteen studies were included in this meta-analysis. Nine articles with ten studies reported the association between teeth loss and EC, pooled analyses indicated that teeth loss was associated with an increased risk of EC (OR,1.44; 95% CI:1.26,1.64). Seven articles with eight studies reported the association between teeth brushing and EC, high frequency of teeth brushing was associated with a lower incidence of EC (OR,0.60; 95%CI:0.44,0.82). Subgroup analyses showed consistent results, teeth loss was associated with an increased risk of EC in Asia (OR,1.48; 95% CI: 1.29,1.70), and high frequency of teeth brushing was associated with a lower incidence of EC (OR,0.65; 95%CI:0.48,0.90). No significant publication bias existed.Conclusions1 A case-control study of the association between oral hygiene and esophageal carcinoma:Low frequency of teeth brushing and teeth loss were possible risk factors for ESCC; Denture wearing after teeth loss can partly weaken the elevated ECSS risk caused by teeth loss.2 Teeth loss, teeth brushing and esophageal carcinoma:a meta-analysis:Teeth loss might be a risk factor for EC; Teeth brushing might be a protective factor for EC.