Green tea consumption and breast cancer risk or recurrence: a meta-analysis

Abstract

Green tea is a commonly consumed beverage in Asia and has been suggested to have anti-inflammatory and possible anti-carcinogenic properties in laboratory studies. We sought to examine the association between green tea consumption and risk of breast cancer incidence or recurrence, using all available epidemiologic evidence to date. We conducted a systematic search of five databases and performed a meta-analysis of studies of breast cancer risk and recurrence published between 1998 and 2009, encompassing 5,617 cases of breast cancer. Summary relative risks (RR) were calculated using a fixed effects model, and tests of heterogeneity across combined studies were conducted. We identified two studies of breast cancer recurrence and seven studies of breast cancer incidence. Increased green tea consumption (more than three cups a day) was inversely associated with breast cancer recurrence (Pooled RR = 0.73, 95% CI: 0.56-0.96). An analysis of case-control studies of breast cancer incidence suggested an inverse association with a pooled RR of 0.81 (95% CI: 0.75, 0.88) while no association was found among cohort studies of breast cancer incidence. Combining all studies of breast cancer incidence resulted in significant heterogeneity. Available epidemiologic evidence supports the hypothesis that increased green tea consumption may be inversely associated with risk of breast cancer recurrence. The association between green tea consumption and breast cancer incidence remains unclear based on the current evidence.

Cancer Chemoprevention by Dietary Polyphenols

“…An inverse association between green tea and breast cancer risk was reported from case-control data, while no association was observed from cohort data [64]. The nested case-control study reported no association [65], so even if it had been included as a cohort study in the pooled analyses, the overall finding would have remained the same.…”

“…The most recent meta-analysis included 7 (2 cohort, 1 nested case-control and 4 casecontrol) epidemiological studies of green tea and breast cancer that were published as of December 2008 [64]. An inverse association between green tea and breast cancer risk was reported from case-control data, while no association was observed from cohort data [64].…”

Tea and human health: biomedical functions of tea active components and current issues

“…Four were population-based studies conducted among Asians in USA and Europe Seely et al, 2005;Ogunleye et al, 2010), one in Shanghai, China (Shrubsole et al, 2009), and one hospital-based study was in Zhejiang Province, China (Zhang et al, 2007). All these six studies showed significant breast cancer risk reduction among the population with regular green tea drinking.…”

Green Tea Catechins -Pharmacokinetic Properties and Health Beneficial Effects

“…Because catechin absorption from the intestines to the bloodstream is relatively low [4], a high dose of about10 cups/d in addition to along duration of green tea consumption maybe necessary to achieve an inverse association between green tea consumption and cancer incidence. Although inconsistent results have been observed in a case-controlled study and a prospective study, Li et al showed that there was a statistically significant 19% reduction of breast cancer incidence among woman with high green tea intake in the most recent meta-analysis of two cohort studies and five casecontrolled studies [34][35][36][37][38][39][40][41].…”