Meta-analysis of black tea consumption and breast cancer risk: update 2013

Black tea is a commonly consumed beverage in the world, comprising approximately 80% of all tea consumed. We sought to examine the association between black tea consumption and risk of breast cancer, using all available epidemiologic evidence to date. PubMed, EMBASE, ISI Web of Science, Chinese National Knowledge Infrastructure Database, and China Biological Medicine Database were used to search for citations using the MeSH terms as "breast neoplasm" AND "black tea." Then we performed a meta-analysis of studies of breast cancer risk published between 1985 and 2013 by using RevMan 5.0 software. The results showed that no association between black tea consumption and breast cancer risk in overall [odds ratio (OR) = 0.97; 95% confidence interval (CI) = 0.89-1.05]. We further performed a stratified analysis according to region (United States/Europe). Black tea consumption did not decrease breast cancer risk in the United States (OR = 0.91; 95% CI = 0.78-1.07) and in Europe (OR = 0.99; 95% CI = 0.93-1.06). In addition, the summary OR from all cohort studies (OR = 1.04, 95% CI = 0.91-1.18) or all case-control studies (OR = 0.95, 95% CI = 0.88-1.02) showed black tea intake has no effects on breast cancer risk. However, the association between black tea consumption and breast cancer incidence remains unclear based on the current evidence. Further well-designed large studies are needed to confirm our result.