Soy cuts breast cancer risk - study

Eating lots of soy foods may help prevent breast cancer, according to a study in the Sept 29, 2009 issue of Cancer Science.

The study led by Zhang C and colleagues of The Chinese University of Hong Kong showed women who ate the highest amounts of soy protein and isoflavone were at lower risk of breast cancer.

Zhang et al. compared soy consumption by 438 Chinese women in Guangdong Province with primary breast cancer and 438 age-matched healthy women and found there was an inverse association between soy intake and breast cancer risk.

Women who had the highest intake of soy isoflavone were at 46 percent reduced risk of breast cancer compared to those who consumed the lowest amounts, Zhang and colleagues found.  And the highest intake of soy protein was linked to 38 percent reduced risk of the disease.

The preventative effect of soy food was found for all types of estrogen receptor (ER) and / or progesterone receptor status of breast cancer.

The inverse association was particularly significant among postmenopausal women.

The researchers concluded that "This study suggests that consumption of soy food, soy isoflavone, is inversely associated with the risk of breast cancer. The protective effects of soy did not seem to differ by ER and PR breast cancer status."

Breast cancer is diagnosed in more than 170,000 women each year in the United States and the disease and its complications kill about 50,000 annually.