Patients with hormone-sensitive cancers may lower their risk of breast cancer recurrence by increasing their soy intake, according to a study published in the Canadian Medical Association Journal (2010 Oct 18. [Epub ahead of print]).

To investigate the effects of soy isoflavones on breast cancer patients receiving adjuvant endocrine therapy, researchers at the Cancer Hospital of Harbin Medical University in Harbin, China conducted a study involving 524 women who had surgery for breast cancer and were followed afterwards for between 5 to 6 years.

“Compared with postmenopausal patients in the lowest quartile of soy isoflavone intake, those in the highest quartile had a significantly lower risk of recurrence,” wrote the study’s authors. “The recurrence rate of estrogen- and progesterone- positive breast cancer was 12.9% lower among patients in the highest quartile of soy isoflavone intake than among those in the lowest quartile, and was 18.7% lower for patients receiving anastrozole therapy in the highest quartile.”

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However, researchers reported that there was no effect on overall survival in postmenopausal women and no association between soy intake and survival in premenopausal women.