Researchers led by Raymond Bergan, MD, of Northwestern University Feinberg School of Medicine in Chicago, found that genistein—a natural substance in soy—inhibits prostate cancer (PCa) cells from becoming metastatic.

This beneficial effect was observed in a phase 2 randomized study involving 38 men with localized PCa, genistein given once daily in pill form one month prior to surgery. Researchers examined the cancer cells from patients’ prostates after surgery and found that genistein increased expression of genes that suppress invasion of cancer cells and decreased expression of genes that enhance invasion.