Public release date: 14-Mar-2008

PHILADELPHIA – A compound found in soybeans almost completely prevented the spread of human prostate cancer in mice, according to a study published in the March 15 issue of Cancer Research, a journal of the American Association for Cancer Research.

Researchers say that the amount of the chemical, an antioxidant known as genistein, used in the experiments was no higher than what a human would eat in a soybean-rich diet.

Investigators from Northwestern University found that genistein decreased metastasis of prostate cancer to the lungs by 96 percent compared with mice that did not eat the compound in their chow – making the study the first to demonstrate genistein can stop prostate cancer metastasis in a living organism.

“These impressive results give us hope that genistein might show some effect in preventing the spread of prostate cancer in patients,” said the study’s senior investigator, Raymond C. Bergan, MD, director of experimental therapeutics for the Robert H. Lurie Comprehensive Cancer Center of Northwestern University.

“Diet can affect cancer and it doesn’t do it by magic,” Bergan said. “Certain chemicals have beneficial effects and now we have all the preclinical studies we need to suggest genistein might be a very promising chemopreventive drug.”

Bergan and his team have previously demonstrated in prostate cancer cell cultures that genistein inhibits detachment of cancer cells from a primary prostate tumor and represses cell invasion. It does this by blocking activation of p38 MAP kinases, molecules which regulate pathways that activate proteins that loosen cancer cells from their tight hold within a tumor, pushing them to migrate. “In culture, you can actually see that when genistein is introduced, cells flatten themselves in order to spread out and stick strongly to nearby cells,” he said.