Soy isoflavones consumption and risk of breast cancer incidence or recurrence: a meta-analysis of prospective studies
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Numbers of epidemiologic studies assessing soy consumption and risk of breast cancer have yielded inconsistent results. We aimed to examine the association between soy isoflavones consumption and risk of breast cancer incidence or recurrence, by conducting a meta-analysis of prospective studies. We searched for all relevant studies with a prospective design indexed in PUBMED through September 1st, 2010. Summary relative risks (RR) were calculated using fixed- or random-effects models. Pre-specified stratified analyses and dose–response analysis were also performed. We identified 4 studies of breast cancer recurrence and 14 studies of breast cancer incidence. Soy isoflavones consumption was inversely associated with risk of breast cancer incidence (RR = 0.89, 95% CI: 0.79–0.99). However, the protective effect of soy was only observed among studies conducted in Asian populations (RR = 0.76, 95% CI: 0.65–0.86) but not in Western populations (RR = 0.97, 95% CI: 0.87–1.06). Soy isoflavones intake was also inversely associated with risk of breast cancer recurrence (RR = 0.84, 95% CI: 0.70–0.99). Stratified analyses suggested that menopausal status may be an important effect modifier in these associations. We failed to identify a dose–response relationship between total isoflavones intake and risk of breast cancer incidence. Our study suggests soy isoflavones intake is associated with a significant reduced risk of breast cancer incidence in Asian populations, but not in Western populations. Further studies are warranted to confirm the finding of an inverse association of soy consumption with risk of breast cancer recurrence.
KeywordsSoybeans Isoflavones Breast cancer Prospective studies Meta-analysis
J-Y D was responsible for the literature search, data analyses, and writing of the manuscript. L-Q Q was responsible for designing the research, interpreting the data and results, and revising the manuscript.
Conflicts of interest
None of the authors had declared a conflict of interest.
- 1.American Cancer Society (2007) Global cancer facts and figures 2007. American Cancer Society, AtlantaGoogle Scholar
- 2.American Cancer Society (2009) Breast cancer facts and figures 2009–2010. American Cancer Society, AtlantaGoogle Scholar
- 18.den Tonkelaar I, Keinan-Boker L, Veer PV, Arts CJ, Adlercreutz H, Thijssen JH, Peeters PH (2001) Urinary phytoestrogens and postmenopausal breast cancer risk. Cancer Epidemiol Biomarkers Prev 10(3):223–228Google Scholar
- 21.Grace PB, Taylor JI, Low YL et al (2004) Phytoestrogen concentrations in serum and spot urine as biomarkers for dietary phytoestrogen intake and their relation to breast cancer risk in European prospective investigation of cancer and nutrition-norfolk. Cancer Epidemiol Biomarkers Prev 13(5):698–708PubMedGoogle Scholar
- 25.Hedelin M, Lof M, Olsson M, Adlercreutz H, Sandin S, Weiderpass E (2008) Dietary phytoestrogens are not associated with risk of overall breast cancer but diets rich in coumestrol are inversely associated with risk of estrogen receptor and progesterone receptor negative breast tumors in Swedish women. J Nutr 138(5):938–945PubMedGoogle Scholar
- 26.Iwasaki M, Inoue M, Otani T, Sasazuki S, Kurahashi N, Miura T, Yamamoto S, Tsugane S (2008) Plasma isoflavone level and subsequent risk of breast cancer among Japanese women: a nested case–control study from the Japan Public Health Center-based prospective study group. J Clin Oncol 26(10):1677–1683CrossRefPubMedGoogle Scholar