the "soy story" is a complicated one

[Lani]

and neu + cancers in mice are ER- I learned from researchers at ASCO!

Mol Nutr Food Res. 2008 Jul 24. [Epub ahead of print]

Reduced mammary tumor progression in a transgenic mouse model fed an isoflavone-poor soy protein concentrate.

Chiesa G, Rigamonti E, Lovati MR, Disconzi E, Soldati S, Sacco MG, Catò EM, Patton V, Scanziani E, Vezzoni P, Arnoldi A, Locati D, Sirtori CR.
Department of Pharmacological Sciences, University of Milano, Italy. Fax: +39-02-50318328.
Dietary exposure to soy has been associated with reduced breast cancer incidence. Soy isoflavones and protein components, such as protease inhibitors and the lunasin peptide, have been indicated as potential agents reducing carcinogenesis. In this study, the effect of soy-based diets was evaluated in a transgenic mouse model of breast carcinoma, overexpressing the neu oncogene. Neu female mice were fed for 20 wk a soy- and isoflavone-free diet (IFD), 4RF21 laboratory mouse diet, soy-based, thus isoflavone-rich (STD), or AIN-76-based semisynthetic diets with a soy protein isolate (SPI) or an isoflavone-poor soy protein concentrate (IPSP) as protein source. Mice were then sacrificed and tumors removed. Mammary tumor weights were not different in SPI versus IFD and STD fed mice. In contrast, mice fed IPSP showed reduced tumor progression versus IFD and STD groups (p < 0.05). Moreover, IPSP fed mice showed lower bromo-2'-deoxyuridine (BrdU) incorporation into breast tumor cells compared to STD and SPI fed animals (p < 0.02). Lung metastases were detected in 80% of IFD fed mice, in 70% of mice fed STD and SPI, and only in 50% of the IPSP fed animals. These results indicate that a diet containing an isoflavone-poor soy protein concentrate may inhibit breast tumor progression and metastasis development.
PMID: 18655005 [PubMed - as supplied by publisher]

[Gina]

and 2) there may be other active ingredients in soy besides the phytoestrogens that are beneficial for folks who are her-2 positive...most notably, the high magnesium levels of soy and other bean foods. Many patients with her-2 mediated disease have low levels of magnesium, most notable by low platelet levels...and intense cravings for chocolate (rich in magnesium).

You will note that the "winning" diet was isoflavone poor, not completely isoflavone - free, and mice fed a soy free and isoflavone -free diet did not do well. I still say that it is the moderate boost of moderate phytoestrogen to the immune system is what is key here. At its most basic root, her-2 mediated disease is a combination of a genetically compromised immune system of a certain kind and an environmentally acquired infection, be it bacterial, viral, or fungal, although my vote still goes for bacterial.

Always good to read your "finds", Lani.


Best guess,
Gina