Study indicates soy foods safe after breast cancer
In a shift from the popular thinking among physicians and patients that breast cancer survivors should avoid soy foods, new evidence indicates that eating soy may actually be beneficial.
A study of more than 18,000 women with a history of breast cancer diagnosed between ages 20 and 83 shows that soy food intake did not increase their risk of breast cancer recurrence. This research contradicts the theory that estrogen-like effects from soy isoflavones might cause breast tumors to grow. The study looked only at the consumption of soy foods, not supplements.
“If you regularly eat soy, you don’t need to worry or avoid it,” says study researcher Xiao Oh Shu, MD, PhD, a professor of medicine at Vanderbilt University Medical Center in Nashville, Tenn. “Soy has many anti-cancer properties, antioxidants, nutrients, micronutrients, or vitamins that may contribute to its beneficial effect on health.”
They found that women who consumed more than 23 milligrams of soy per day (about one glass of soy milk or a half cup of tofu), had a 15 percent reduced risk of breast cancer recurrence, compared with women consuming less than 0.48 milligrams of soy. These results were not, however, considered statistically significant.
And while there are many documented health benefits of soy, patients and physicians still wonder about its safety for breast cancer survivors. This study may be the first step in clearing up the confusion. Says Leif Ellison, MD, PhD, of the Gillette Center for Breast Health at the University of Massachusetts General Hospital Cancer Center in Boston: “There has been some theoretical concern that soy has molecules that resemble estrogen which may increase risk of breast cancer recurrence. But... this study suggested a benefit in terms of overall health and breast cancer recurrence.” Ellison goes on to say that he will counsel his patients differently in the future. “This is a strong study and it gives us a lot of support to say you should not be eliminating soy and if anything, you could increase soy in your diet.”
This research is considered preliminary until published in a peer-reviewed journal, and was presented at the 2011 annual meeting of the American Association for Cancer Research.
Much information is available on the internet about the relationship between soy and breast cancer. An introduction to the issue can be found through breastcancer.org, this article regarding vegetarian nutrition, or this piece published in the Chicago Tribune. A simple Google search will yield many additional results on this topic.
June 6, 2011