Effects of isoflavones on breast density in pre- and post-menopausal women: a systematic review and meta-analysis of randomized controlled trials

Abstract

BACKGROUNDIsoflavones from soy and red clover exert modest hormonal effects in women, but the relevance to risk of breast cancer is unclear. The aim of this meta-analysis was to assess the effects of isoflavone-rich foods or supplements on a biomarker of breast cancer risk, women's mammographic density.METHODSElectronic searches were performed on The Cochrane Library, Medline and EMBASE (to June 2009), and reference lists and trial investigators were consulted to identify further studies. Randomized controlled trials (RCTs) of isoflavone-rich foods or supplements versus placebo with a duration of at least 6 months were included in our analysis. Inclusion/exclusion, data extraction and validity assessment were carried out independently in duplicate, and meta-analysis used to pool study results. Subgrouping, sensitivity analysis, assessment of heterogeneity and funnel plots were used to interpret the results.RESULTSEight RCTs (1287 women) compared isoflavones with placebo for between 6 months and 3 years. Meta-analysis suggested no overall effect of dietary isoflavones on breast density in all women combined [mean difference (MD) 0.69%, 95% confidence interval (CI) −0.78 to 2.17] or post-menopausal women (MD −1.10%, 95% CI −3.22 to 1.03). However, there was a modest increase in mammographic density in premenopausal women (MD 1.83%, 95% CI 0.25–3.40) without heterogeneity but this effect was lost in one of three sensitivity analyses.CONCLUSIONSIsoflavone intake does not alter breast density in post-menopausal women, but may cause a small increase in breast density in premenopausal women. Larger, long-term trials are required to determine if these small effects are clinically relevant.

Association between Dietary Factors and Breast Cancer Risk among Chinese Females: Systematic Review and Meta-analysis

“…Experiments on rats indicated that the incidence of chemically induced mammary tumors significantly decreased when prepubertal rats were exposed to soy extracts or the isoflavone genistein (Warri et al, 2008). Soy isoflavone is similar to the structure of endogenous estrogen, thus, it is a competitive inhibitor of endogenous estrogen and then protect against breast cancer (Limer et al, 2004;Magee et al, 2004;Hooper et al, 2010). Soy isoflavones also have other protective effects, including antioxidant, antiproliferative, anti-inflammatory and anti-angiogenic effect (Heber, 2004).…”

Les aliments au soja : consommation en France, qualités nutritionnelles et données scientifiques récentes sur la santé

“…De récentes études ont montré que ni les protéines de soja, ni les aliments au soja, ni les compléments alimentaires d'isoflavones n'ont d'effet sur des marqueurs du risque de cancer du sein comme la densité mammographique (Hooper, 2010 ;Wu, 2015) ou la prolifération des cellules mammaires (Khan et al, 2012 ;Palomares, 2004 ;Sartippour, 2004 ;Shike, 2014).…”

Repression of mammary adipogenesis by genistein limits mammosphere formation of human MCF-7 cells

“…This study provides new mechanistic insights that may partly explain the favorable association of soy food intake with decreased breast cancer risk in the human population (Wu et al 2008, Hooper et al 2010 and in rodent models of human breast cancer (Jin & MacDonald 2002, Verheus et al 2007, Wu et al 2008. Using a recently characterized mouse MSF cell line that can differentiate into adipocytes with hormonal treatments, we provide evidence for the specificity of the antiadipogenic effect of the major soy isoflavone GEN on mammary adipose cells.…”

“…High consumption of soy-rich foods containing genistein (GEN) is considered to partly underlie the lower breast cancer incidence in Asian women than in their western counterparts (Wu et al 2008, Hooper et al 2010. The antitumor effects of soy foods and bioactive GEN have been demonstrated in many rodent models of breast cancer (Jin & MacDonald 2002, Su et al 2007b, Verheus et al 2007, Wu et al 2008 to occur through multiple mechanisms.…”