Soy reduces the risk of specific breast cancers

October 20, 2008

High intake of soy foods specifically reduce the risk of estrogen receptor (ER)-positive tumors and human epidermal growth factor receptor 2 (HER2)-negative tumors in a study of  678 women with breast cancer and 3,390 cancer-free controls matched by age and menopausal status Japanese researchers report in the International Journal of Cancer. For women who ate the most soy compared with those who ate the least amount the odds of having ER-positive breast cancer were reduced by 26 percent and for women with HER2-negative breast cancer, the reduced risk was 22 percent.

However, the research team found that "when the three receptors were jointly examined, a reduced risk was observed only for patients with ER-positive/PR-positive/HER2-negative tumors," with a 27-percent reduction seen only in the women who ate the most soy.  "These findings are biologically plausible, and suggest a potential benefit of soybean products in the prevention of breast cancer," the investigators conclude. The study is published in the October 2009 issue of the International Journal of Cancer.