Abstract
Background and Objective: Controversial results of the association between tea (black tea, green tea, mate, and oolong tea) consumption and risk of bladder cancer were reported among epidemiological studies. Thus, we performed a meta-analysis of observational studies to investigate the association.Methods: We searched the PubMed and Embase for studies of tea consumption and bladder cancer that were published in any language up to March, 2016. Cohort or case-control studies were included in the meta-analysis. All statistical analyses were performed in Stata 12.0 software. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess the relationship between tea consumption and risk of bladder cancer.Results: Totally, 25 case-control studies (15 643 cases and 30 795 controls) and seven prospective cohort studies (1807 cases and 443 076 participants) were included. The meta-analysis showed that tea consumption was not significantly associated with bladder cancer risk (OR = 0.96, 95% CI 0.86–1.06) (in a comparison of highest vs. lowest category). No non-linearity association was observed between tea consumption and bladder cancer risk (P = 0.51 for non-linearity). Specific analysis for black tea, green tea, and mate yielded similar results. The dose-response analysis showed the summary OR for an increment of 1 cup/day of tea consumption was 1.01 (95% CI 0.97–1.05).Conclusion: Results based on current meta-analysis indicated that no significant association was observed between tea consumption and risk of bladder cancer.
Highlights
Bladder cancer is a very common disease worldwide, accounting for ∼429 800 new cases and 165 100 deaths occurred in 2012 worldwide (Torre et al, 2015)
PubMed and Embase were searched for studies examining the relationship between tea consumption and bladder cancer that were published in any language up to March, 2016
For studies reported the information by subsets, we summarized the odds ratios (ORs) with 95% confidence intervals (CIs) of the subsets in a fixed-effect model before aggregating them into overall analysis
Summary
Bladder cancer is a very common disease worldwide, accounting for ∼429 800 new cases and 165 100 deaths occurred in 2012 worldwide (Torre et al, 2015). The relationship between tea consumption and risk of bladder cancer is biologically plausible (Lu et al, 1999; Sagara et al, 2010), epidemiological studies on this theme have obtained inconsistent results. Two meta-analyses of observation studies concluded that tea consumption was not associated with an elevated risk of bladder cancer (Zeegers et al, 2001b; Qin et al, 2012). A recently published meta-analysis suggested that tea consumption was associated with decreased risk of bladder cancer in Western countries (Zhang et al, 2015). In order to clarify the relationship between tea consumption and the risk of bladder cancer, we performed the present dose-response meta-analysis of all published observational studies. Controversial results of the association between tea (black tea, green tea, mate, and oolong tea) consumption and risk of bladder cancer were reported among epidemiological studies. We performed a meta-analysis of observational studies to investigate the association
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
