Coffee consumption and risk of lung cancer: a meta-analysis.
ABSTRACT Epidemiologic studies have evaluated the potential association between coffee consumption and lung cancer risk. However, results were inconsistent. To clarify the role of coffee in lung cancer, we conducted a meta-analysis on this topic. We searched PubMed and EMBASE databases (from 1966 to January 2009) and the reference lists of retrieved articles. Study-specific risk estimates were pooled using random-effects model. Five prospective studies and 8 case-control studies involving 5347 lung cancer cases and 104,911 non-cases were included in this meta-analysis. The combined results indicated a significant positive association between highest coffee intake and lung cancer [relative risk (RR)=1.27, 95% confidence interval (CI)=1.04-1.54). Furthermore, an increase in coffee consumption of 2 cups/day was associated with a 14% increased risk of developing lung cancer (RR=1.14, 95% CI=1.04-1.26). In stratified analyses, the highest coffee consumption was significantly associated with increased risk of lung cancer in prospective studies, studies conducted in America and Japan, but borderline significantly associated with decreased risk of lung cancer in non-smokers. In addition, decaffeinated coffee drinking was associated with decreased lung cancer risk, although the number of studies on this topic was relative small. In conclusion, results from this meta-analysis indicate that high or an increased consumption of coffee may increase the risk of lung cancer. Because the residual confounding effects of smoking or other factors may still exist, these results should be interpreted with caution.
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ABSTRACT: Statistics sits right at the heart of scientific endeavour in respiratory medicine and many other disciplines. In this introductory article, some key epidemiological concepts such as representativeness, random sampling, association and causation, and confounding are reviewed. A brief introduction to basic statistics covering topics such as frequentist methods, confidence intervals, hypothesis testing, P values and Type II error is provided. Subsequent articles in this series will cover some modern statistical methods including regression models, analysis of repeated measures, causal diagrams, propensity scores, multiple imputation, accounting for measurement error, survival analysis, risk prediction, latent class analysis and meta-analysis.Respirology 01/2014; 19(1):9-13. · 3.50 Impact Factor
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ABSTRACT: Excretion of odorants and their metabolites into human urine was investigated in urine samples obtained from 14 volunteers after consumption of common dosages of coffee with respect to blank urine samples prior to coffee consumption. Analyses were targeted both on common potent odor constituents of the coffee beverage, as characterized by aroma extract dilution analysis, as well as on volatile constituents of coffee occurring at elevated concentrations and thereby representing quantitatively dominating compounds in the coffee volatile fraction. Identification and quantification of the target substances was accomplished by two-dimensional high resolution gas chromatography mass spectrometry (2D-HR-GC-MS; heart-cut technique) in conjunction with stable isotope dilution assays. Quantification was made on free volatile or odoros marker substances in the urine and their glucuronidated derivatives. Data revealed that some odorants were present at considerably elevated concentrations after the ingestion of coffee. This was confirmed by the odor profiles of the respective urine samples during sensory analysis.Metabolomics 04/2014; 10(2). · 3.97 Impact Factor
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ABSTRACT: Tea and coffee are the most commonly consumed beverages in the worldwide. The relationship between tea and coffee consumption on the risk of laryngeal cancer was still unclear. Relevant studies were identified by searching electronic database (Medline and EMBASE) and reviewing the reference lists of relevant articles until Oct. 2013. Observational studies that reported RRs and 95% CIs for the link of tea and coffee consumption on the risk of laryngeal cancer were eligible. A meta-analysis was obtained to combine study-specific RRs with a random-effects model. A total of 2,803 cases and 503,234 controls in 10 independent studies were identified. The overall analysis of all 10 studies, including the case-control and cohort studies, found that tea drinking was not associated with laryngeal carcinoma (RR = 1.03; 95% CI: 0.66-1.61). However, coffee consumption was significantly associated with the laryngeal carcinoma (RR = 1.47; 95% CI: 1.03-2.11). A dose-response relationship between coffee intake and laryngeal carcinoma was detected; however, no evidence of dose-response link between tea consumption and laryngeal carcinoma risk was detected. The results from this meta-analysis of observational studies demonstrate that coffee consumption would increase the laryngeal cancer risk, while tea intake was not associated with risk of laryngeal carcinoma.PLoS ONE 01/2014; 9(12):e112006. · 3.53 Impact Factor