Isoflavones – Mechanism of Action and Impact on Breast Cancer Risk

Abstract

Isoflavones are plant-derived substances with weak estrogenic effects. Asian populations are high consumers of soy products which are rich in isoflavones. The lower breast cancer incidence in Asian women compared with Western women has been associated with the possibility of a preventive isoflavone effect on cancer risk. The aim of this review is to give an overview of current research data on the influence of isoflavones on the risk of primary breast cancer development as well as the risk of recurrence in breast cancer patients. Despite inconsistencies in the available data, an inverse correlation between isoflavone intake and risk of breast cancer is likely. However, a negative impact on breast cancer disease, especially on hormone receptor-positive tumors, cannot be excluded at present.

The Effects of Soy Supplementation on Gene Expression in Breast Cancer: A Randomized Placebo-Controlled Study

“…Pathway analysis of the high-genistein signature revealed overrepresentation of pathways that regulate cell growth and proliferation in tumors of the high-genistein group (P < .001). DAVID analysis of overexpressed genes in the high-genistein group revealed that 18 of 23 categories represented cell cycle functions (Bonferroni P < .001, FDR < 0.01) (Supplementary Table 6, available online) (33). Similarly, IPA revealed that the Top Biological Functions and Network Modules of the 126 DE genes were cellular growth and proliferation, cell cycle, cell death and survival, cell development, and nucleic acid metabolism (P < .001) (Supplementary Figure 2, A and B, and Supplementary Table 7, available online).…”

Commonly Used Methods of Complementary Medicine in the Treatment of Breast Cancer

“…Yet, there are data to support drinking green tea in order to reduce the risk of recurrence [44][45][46]. Whilst isoflavones have the potential to reduce the breast cancer incidence, particularly when consumed on a regular basis beginning before puberty [47], their consumption as secondary prevention after breast cancer appears critical: Particularly in the estrogen-deprived environment under aromatase inhibitors, isoflavones (e.g. genistein from soy) could stimulate hormone receptor-positive cells to divide.…”

Disposition of soy isoflavones in normal human breast tissue

“…Therefore, estrogen-induced cell proliferation has been a major focus in breast cancer research. Despite the substantially lower breast-cancer prevalence in populations with a high soy consumption (1,2), the findings of Allred et al (3)(4)(5)(6)(7) provoked a heated debate about the safety of dietary phytoestrogens, such as isoflavones, especially for patients with existing estrogen-sensitive tumors and women at a high risk of developing breast cancer (1,(8)(9)(10).…”