Does coffee, tea and caffeine consumption reduce the risk of incident breast cancer? A systematic review and network meta-analysis

Abstract

Objective: We aimed to evaluate the association between coffee and/or tea consumption and breast cancer (BC) risk among premenopausal and postmenopausal women and to conduct a network meta-analysis. Design: Systematic review and network meta-analysis. Setting: We conducted a systematic review of electronic publications in the last 30 years to identify case–control studies or prospective cohort studies that evaluated the effects of coffee and tea intake. Results: Forty-five studies that included more than 3 323 288 participants were eligible for analysis. Network meta-analysis was performed to determine the effects of coffee and/or tea consumption on reducing BC risk in a dose-dependent manner and differences in coffee/tea type, menopause status, hormone receptor and the BMI in subgroup and meta-regression analyses. According to the first pairwise meta-analysis, low-dose coffee intake and high-dose tea intake may exhibit efficacy in preventing ER(estrogen receptor)− BC, particularly in postmenopausal women. Then, we performed another pairwise and network meta-analysis and determined that the recommended daily doses were 2–3 cups/d of coffee or ≥5 cups/d of tea, which contained a high concentration of caffeine, particularly in postmenopausal women. Conclusions: Coffee and tea consumption is not associated with a reduction in the overall BC risk in postmenopausal women and is associated with a potentially lower risk of ER− BC. And the highest recommended dose is 2–3 cups of coffee/d or ≥5 cups of tea/d. They are potentially useful dietary protectants for preventing BC.

A Mendelian randomization study of the effect of tea intake on breast cancer

“…Additionally, the summary results of all cohort studies or case-control studies showed no association of black tea intake with breast cancer risk ( 11 ). A network meta-analysis that included 45 cohort and case-control studies found that tea drinking was not related to a lower overall breast cancer risk in postmenopausal women ( 9 ).…”

“…However, there is an unclear consensus in the epidemiological studies on whether tea consumption is beneficial to population health, especially for cancer (8). Several meta-analyses showed that tea was not related to breast cancer risk (9)(10)(11)(12)(13), some studies reported an inverse effect against breast cancer (14)(15)(16), and several studies showed a positive association (17). The reliability of these findings can be easily influenced by cross-sectional design, small sample size, insufficient follow-up period, or different reference groups.…”

Anticarcinogenic potentials of tea catechins

“…A meta-analysis including 3,323,288 participants showed that heavy tea consumption has a preventing effect against ER-BC, especially in the post-menopausal women. Therefore, tea was considered to be a potentially useful dietary protectant for preventing BC and a recommended dose was ≥5 cups/day ( 23 ).…”