Soy Associated with Moderately Lower Breast Cancer Risk
Effect stronger in premenopausal than postmenopausal women, but evidence still mixed
WEDNESDAY, April 5 (HealthDay News) -- Increasing soy consumption may slightly lower breast cancer risk among women in Western nations, according to a meta-analysis published online April 5 in the Journal of the National Cancer Institute. However, the evidence is not strong enough to recommend high-dose isoflavone supplements, they conclude.
Bruce J. Trock, Ph.D., of the Johns Hopkins School of Medicine in Baltimore, and colleagues analyzed the results of 18 case-control or cohort studies of soy consumption and breast cancer risk conducted between 1978 and 2004.
They found that high soy consumption was modestly associated with a lower cancer risk (odds ratio 0.86) for all women, but the results were not statistically significant for Asian women (OR, 0.89), who eat more soy in the traditional diet than women in Western nations.
"Soy intake may be associated with a small reduction in breast cancer risk," the authors write. "However, this result should be interpreted with caution due to potential exposure misclassification, confounding and lack of a dose response. Given these caveats and results of some experimental studies that suggest adverse effects from soy constituents, recommendations for high-dose isoflavone supplementation are premature."
In an editorial, Maria Elena Martinez, Ph.D., of the University of Arizona in Tucson, and colleagues conclude that these results do not help elucidate the role of soy in the etiology of breast cancer.