the association between green tea consumption and breast cancer risk: a systematic review and meta-analysis

background: this systematic review and meta-analysis aimed to critically evaluate the relation between green tea (gt) consumption and the risk of breast cancer.method: electronic databases were systematically searched for english papers. all case-control and cohort studies in addition to randomized clinical trials were included if they assessed the chemopreventive effects of green tea on breast cancer. the quality of included studies was assessed. in the meta-analysis, the odds ratio (or) was calculated based on the results from those who had the highest amount of gt consumed to the data from subjects with the lowest intake.result: this systematic review comprised 44 studies. or in case-control studies suggested that women in the group receiving the highest level of gt had 19% reduction in breast cancer risk compared with those who received the lowest level of gt (summary or= 0.81, p=0.031; 95% ci: 18000.66 to 0.981). or in cohort studies showed no significant difference between women with the highest consumption of gt and those who received it at the lowest level (or=0.99, p=0.94; 951 ci: 0.81 to 1.138). according to the only clinical trial, treatment with gt could not alter the mammographic density compared to placebo.conclusion: epidemiological studies have drawn inconsistent conclusions regarding the association between gt intake and breast cancer risk. nonetheless, it cannot be concluded that gt consumption may decrease the risk of breast cancer. we did not find any statistically significant reduction of breast cancer risk due to gt consumption in case-control nor cohort studies