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PLoS One. 2014 Feb 20;9(2):e89288. doi: 10.1371/journal.pone.0089288. eCollection 2014.

Association between soy isoflavone intake and breast cancer risk for pre- and post-menopausal women: a meta-analysis of epidemiological studies.

Author information

1
Department of Epidemiology and Biostatistics, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
2
Jiangxia Maternal and Child Health Hospital, Wuhan, China.
3
WuXiPRA Clinical Research (Shanghai) Co., Ltd, Shanghai, China.

Abstract

BACKGROUND:

Conclusions drawn from meta-analyses on the association between soy isoflavone intake and breast cancer risk for pre- and post-menopausal women are not fully consistent. These meta-analyses did not explore the influence of different study designs on the pooled results on the basis of distinguishing between pre- and post-menopausal women.

METHODOLOGY AND PRINCIPAL FINDINGS:

We performed a meta-analysis of 35 studies which reported results of association between soy isoflavone intake and breast cancer risk for pre- and/or post-menopausal women, calculated pooled odds ratios and their 95% confidence intervals of pre- and post-menopausal women respectively, and further explored soy isoflavone-breast cancer association on the basis of considering different study regions and designs. Summary results suggested that soy isoflavone intake has a protective effect against breast cancer for both pre- and post-menopausal women. However, they are influenced by study design and region. Pooled ORs of studies carried out in Asian countries suggested that soy isoflavone's protective effect exist in both pre- and post-menopausal women (OR = 0.59, 95%CI: 0.48-0.69 for premenopausal women; OR = 0.59, 95%CI: 0.44-0.74 for postmenopausal women). However, there are some differences between the results pooled from different study designs for women in Asian countries (test for consistency, P = 0.04). Pooled OR of studies on postmenopausal women in Western countries suggested that soy isoflavone intake has a marginally significant protective effect (OR = 0.92; 95%CI: 0.83 ∼ 1.00), but further analyses stratifying by study design found no statistically significant association.

CONCLUSIONS:

We meta-analyzed more and newer research results, and separated women according to menopausal status to explore soy isoflavone-breast cancer association. We founded that soy isoflavone intake could lower the risk of breast cancer for both pre- and post-menopausal women in Asian countries. However, for women in Western countries, pre- or post-menopausal, there is no evidence to suggest an association between intake of soy isoflavone and breast cancer.

PMID:
24586662
PMCID:
PMC3930722
DOI:
10.1371/journal.pone.0089288
[Indexed for MEDLINE]
Free PMC Article

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