Influence of Pre-treatment Saliva Microbial Diversity and Composition on Nasopharyngeal Carcinoma Prognosis.

Background: The human microbiome has been reported to mediate the response to anticancer therapies. However, research about the influence of the oral microbiome on nasopharyngeal carcinoma (NPC) survival is lacking. We aimed to explore the effect of oral microbiota on NPC prognosis. Methods: Four hundred eighty-two population-based NPC cases in southern China between 2010 and 2013 were followed for survival, and their saliva samples were profiled using 16s rRNA sequencing. We analyzed associations of the oral microbiome diversity with mortality from all causes and NPC. Results: Within- and between-community diversities of saliva were associated with mortality with an average of 5.29 years follow-up. Lower Faith's phylogenetic diversity was related to higher all-cause mortality [adjusted hazard ratio (aHR), 1.52 (95% confidence interval (CI), 1.06-2.17)] and NPC-specific mortality [aHR, 1.57 (95% CI, 1.07-2.29)], compared with medium diversity, but higher phylogenetic diversity was not protective. The third principal coordinate (PC3) identified from principal coordinates analysis (PCoA) on Bray-Curtis distance was marginally associated with reduced all-cause mortality [aHR, 0.85 (95% CI, 0.73-1.00)], as was the first principal coordinate (PC1) from PCoA on weighted UniFrac [aHR, 0.86 (95% CI, 0.74-1.00)], but neither was associated with NPC-specific mortality. PC3 from robust principal components analysis was associated with lower all-cause and NPC-specific mortalities, with HRs of 0.72 (95% CI, 0.61-0.85) and 0.71 (95% CI, 0.60-0.85), respectively. Conclusions: Oral microbiome may be an explanatory factor for NPC prognosis. Lower within-community diversity was associated with higher mortality, and certain measures of between-community diversity were related to mortality. Specifically, candidate bacteria were not related to mortality, suggesting that observed associations may be due to global patterns rather than particular pathogens.

Do genetic factors explain the association between poor oral health and cardiovascular disease? A prospective study among Swedish twins.

Epidemiologic studies suggest positive associations between poor oral health and cardiovascular disease. The authors undertook a prospective study among 15,273 Swedish twins (1963-2000) to examine whether genetic factors underlying the 2 diseases could explain previous associations. They estimated hazard ratios and 95% confidence intervals controlling for individual factors and stratifying on twin pairs to control for familial effects. Quantitative genetic analyses estimated genetic correlations between oral diseases and cardiovascular disease outcomes. Tooth loss (hazard ratio (HR) = 1.2, 95% confidence interval (CI): 1.1, 1.4) and periodontal disease (HR = 1.3, 95% CI: 1.0, 1.4) were associated with small excess risks of cardiovascular disease; periodontal disease was also associated with coronary heart disease (HR = 1.4, 95% CI: 1.1, 1.6). Adjustment for genetic factors in co-twin analyses did not appreciably change estimates. In contrast, tooth loss was more strongly associated with coronary heart disease in twin models (HR = 2.1, 95% CI: 1.2, 3.8) compared with adjusting for individual factors alone (HR = 1.3, 95% CI: 1.1, 1.4). There was evidence of shared genetic factors between cardiovascular disease and tooth loss (r(G) = 0.18) and periodontal disease (r(G) = 0.29). Oral disease was associated with excess cardiovascular disease risk, independent of genetic factors. There appear to be common pathogenetic mechanisms between poor oral health and cardiovascular disease.

Oral use of Swedish moist snuff (snus) and risk for cancer of the mouth, lung, and pancreas in male construction workers: a retrospective cohort study.

BACKGROUND: Although classified as carcinogenic, snuff is used increasingly in several populations. Scandinavian moist snuff (snus) has been proposed as a less harmful alternative to smoking, but precise data on the independent associations of snus use with site-specific cancers are sparse. We aimed to assess the risks for cancer of the oral cavity, lung, and pancreas. METHODS: Detailed information about tobacco smoking and snus use was obtained from 279 897 male Swedish construction workers in 1978-92. Complete follow-up until end of 2004 was accomplished through links with population and health registers. To distinguish possible effects of snus from those of smoking, we focused on 125 576 workers who were reported to be never-smokers at entry. Adjusted relative risks were derived from Cox proportional hazards regression models. FINDINGS: 60 cases of oral, 154 of lung, and 83 of pancreatic cancer were recorded in never-smokers. Snus use was independently associated with increased risk of pancreatic cancer (relative risk for ever-users of snus 2.0; 95% CI 1.2-3.3, compared with never-users of any tobacco), but was unrelated to incidence of oral (0.8, 95% CI 0.4-1.7) and lung cancer (0.8, 0.5-1.3). INTERPRETATION: Use of Swedish snus should be added to the list of tentative risk factors for pancreatic cancer. We were unable to confirm any excess of oral or lung cancer in snus users.

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.