A study (published in Canadian Medical Association Journal) reports that postmenopausal women with a prior history of estrogen receptor positive breast cancer had a significantly lower risk (33% less!!) of breast cancer recurrence when they consumed higher quantities of soy foods compared to those women who ate smaller quantities. Estrogen receptor positivity or sensitivity means that the breast cancer is stimulated by estrogen.
The authors also reported that he risk of breast cancer recurrence was further reduced in the highest soy consumption patients who were also taking a commonly prescribed hormonal anti-cancer medication (Anastrazole.)
In a study (published in the Journal of the American Medical Association) which examined women with a prior history of breast, the authors reported that soy food consumption (in an amount typically found in an Asian diet) was significantly associated with a decreased risk of death and breast cancer recurrence. Importantly, these results did not vary based on the estrogen-receptor status of the tumor. This implies, that soy may be preventing breast cancer growth through an estrogen-independent mechanism. (read more here)
Soy (a “phytoestrogen”) has natural estrogen-like qualities and therefore is surrounded by controversy in terms of recommending or avoiding its’ consumption in patients with a history of estrogen sensitive tumors. Research seems to suggest that consumption of whole soy plants and products (i.e. soy beans, tofu, tempeh, etc.) is likely a safe and beneficial protein source with anti-cancer effects with estrogen sensitive tumors (whereas extracted soy isolates may actually stimulate estrogen sensitive tumors.)
