THE QUESTION Eating a lot of soy-based foods is believed to help prevent breast cancer. Might soy supplements also help?

THIS STUDY involved 98 women, most 48 to 50 years old and about equally divided between pre- and post-menopausal status. All were considered at high risk for breast cancer but were otherwise healthy. They were randomly assigned to take soy supplements or a placebo daily for six months. Participants were not to eat any foods containing soy or take any hormone treatments. Breast biopsies were done at the start and end of the study to extract and measure epithelial cells, which are considered early cancer cells, and laboratory analyses were done to determine the level of a protein that indicates cancer cell growth. Overall, there was virtually no difference at the end of the study between women who did and did not take soy supplements. Among the pre-menopausal women, however, the protein marker showed an increase in cancer cells among those taking soy. A similar change was not seen, on average, in the post-menopausal women.

WHO MAY BE AFFECTED? Women at above-average risk for breast cancer, which one in eight U.S. women can expect to develop. Risk increases as a woman ages. Other factors that make this cancer more likely in some women include a certain genetic makeup, early menstruation and late menopause. Women, especially those who are healthy, often seek nondrug means, such as soy, to protect themselves from breast cancer.

CAVEATS The study was short-lived. Many experts believe that the cancer-preventive benefits of soy seen in primarily Asian populations stem from consumption early in life, which the study did not test.

FIND THIS STUDY February issue of Cancer Prevention Research (cancerpreventionresearch.aacrjournals.org).

LEARN MORE ABOUT breast cancer at www.cancer.org. Learn about soy at nccam.nih.gov.

Linda Searing

The research described in Quick Study comes from credible, peer-reviewed journals. Nonetheless, conclusive evidence about a treatment's effectiveness is rarely found in a single study. Anyone considering changing or beginning treatment of any kind should consult with a physician.