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.”

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.