title: Association between soy isoflavone intake and breast cancer risk for pre- and post-menopausal women: a meta-analysis of epidemiological studies.
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.
  
  
  RESULTS
  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.
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Meinan
authors.initials: M
authors.lastname: Chen
authors.affiliation: Jiangxia Maternal and Child Health Hospital, Wuhan, China.
authors.forename: Yanhua
authors.initials: Y
authors.lastname: Rao
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zheng
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Shiqing
authors.initials: S
authors.lastname: Wei
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Li
authors.affiliation: WuXiPRA Clinical Research (Shanghai) Co., Ltd, Shanghai, China.
authors.forename: Tong
authors.initials: T
authors.lastname: Guo
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Yin
mesh_terms: D001943:Breast Neoplasms / Q000517:prevention & control*; D016022:Case-Control Studies; D016021:Epidemiologic Studies; D005260:Female; D006801:Humans; D007529:Isoflavones / Q000008:administration & dosage*; D016017:Odds Ratio; D018570:Risk Assessment; D030262:Soybean Proteins / Q000494:pharmacology*
chemical_list: D007529:Isoflavones; D030262:Soybean Proteins