Journal Article

Green tea, black tea and breast cancer risk: a meta-analysis of epidemiological studies

Can-Lan Sun, Jian-Min Yuan, Woon-Puay Koh and Mimi C. Yu

in Carcinogenesis

Volume 27, issue 7, pages 1310-1315
Published in print July 2006 | ISSN: 0143-3334
Published online November 2005 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/bgi276
Green tea, black tea and breast cancer risk: a meta-analysis of epidemiological studies

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Experimental studies have shown that tea and tea polyphenols have anti-carcinogenic properties against breast cancer. A number of epidemiologic studies, both case–control and cohort in design, have examined the possible association between tea intake and breast cancer development in humans. This meta-analysis included 13 papers which examined populations in eight countries and provided data on consumption of either green tea or black tea, or both in relation to breast cancer risk. Summary odds ratios (ORs) for highest versus non/lowest tea consumption level were calculated based on fixed and random effects models. Heterogeneity between studies was examined via the Q statistics. For green tea, the combined results from the four studies indicated a reduced risk of breast cancer for highest versus non/lowest intake (OR = 0.78, 95% CI = 0.61–0.98). For black tea, conflicting results were observed in case–control versus cohort studies. The combined results from the eight case–control studies showed a minor inverse association between black tea consumption and risk of breast cancer (OR = 0.91, 95% CI = 0.84–0.98). This inverse association was stronger in hospital-based (OR = 0.77, 95% CI = 0.50–1.19) than population-based case–control studies (OR = 0.94, 95% CI = 0.81–1.09). Five cohort studies demonstrated a modest increase in risk associated with black tea intake (OR = 1.15, 95% CI = 1.02–1.31). The results of this meta-analysis indicate a lower risk for breast cancer with green tea consumption. Available data suggest a possible late-stage, promotional effect of black tea on breast carcinogenesis.

Keywords: CI, confidence interval; EGCG, epigallocatechin gallate; HCC, hospital-based case–control study; OR, odds ratio; PCC, population-based case–control study; RR, relative risk

Journal Article.  4739 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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