Eating more soy may boost the effects of tamoxifen, a drug that prevents breast cancer in high-risk women, according to a new study presented at the annual meeting of the American Association of Cancer Research in New Orleans on March 28.

Researchers from the University of Illinois at Chicago investigated carcinogen-induced tumors in rats and found that tamoxifen reduced them by 29 percent, from 7.9 tumors per rat to 5.6 tumors on average. Soy alone reduced the number of tumors by 37 percent. The interesting thing they found was that by combining soy and tamoxifen, the tumors were reduced even further, by an impressive 62 percent.

"While we do not know whether these results apply to women who, because of environmental factors or genetic predisposition, are at high risk for developing breast cancer, our study would suggest that a human trial is warranted," says Andreas Constantinou, associate professor of surgical oncology at UIC. Constantinou and his colleagues are now studying the origins of the additive effects of soy seen in this animal study.