Study shows soy reduces risk of prostate cancerUSA (Environmental News Network ) 7/6/2001-- Men at risk of prostatecancer might want to include more tofu and soy milk in their dietsfollowing the results of a study at the University of California at DavisCancer Center. Although the study was conducted with mice, and resultsmust be replicated with humans, researchers found that a chemical found insoy slowed prostate cancer growth in mice and caused prostate cancer cellsto die.The soy chemical found to reduce prostate cancer in mice is calledgenistein, one of two compounds in soy that belong to a family ofchemicals known as isoflavones. Isoflavones are phytoestrogens, plantbased chemicals that mimic the effects of estrogen in the body.Researchers theorize that the prevalence of soy in Asian diets may be onereason why men in Asia have a lower rate of prostate cancer than men inthe United States. Prostate cancer is the most common cancer amongAmerican men.Ralph deVere White, director of the UC Davis Cancer Center and chair ofthe Department of Urology at the UC Davis Medical Center, presented theresults of this study at the annual meeting of the American UrologicalAssociation in Anaheim this week."We've identified the mechanisms by which genistein may work in prostatecancer, and it's consistent with other studies of soy," said deVere White."While we are encouraged by these results, we need to test genistein inpatients with prostate cancer to be certain of its effectiveness."The American Cancer Society estimates that there will be 334,500 new casesof prostate cancer in the United States this year. Prostate cancer isexpected to kill over 40,000 American men this year.For the UC Davis study, scientists tested a commercially made extract ofgenistein on mice bred to develop prostate cancer and on metastaticprostate cancer cell lines.In mice, genistein reduced prostate cancer tumor growth.In the tissue culture, genistein increased the production of p21, a genethat regulates cell growth, and it reduced the production of vascularendothelial growth factor, a protein that helps cancer grow. These factorscaused cancer cells to die.UC Davis researchers are now evaluating the effects of genistein in menwho have been diagnosed with slow growing prostate cancer. The cancercenter intends to enroll 70 men in a pilot study to see if genisteinlowers levels of prostate specific antigen, a tumor marker for prostatecancer.Men who have chosen not to receive treatment for prostate cancer or whohave undergone treatment and whose prostate specific antigen levels arerising slowly are eligible to volunteer for the trial. Results will beknown in a year.It is unlikely genistein would become a stand alone treatment for prostatecancer, said deVere White. "But we hope it could be used in conjunctionwith conventional therapy or as a preventive drug, if it indeed lowersprostate specific antigen."Other components in foods have been found to reduce prostate cancer.Studies now show that an all natural supplement of lycopene, the chemicalthat makes tomatoes red, may help prevent and treat prostate cancer.Omer Kucuk, M.D., professor of Medicine and Oncology, and colleagues atthe Karmanos Cancer Institute in Detroit, Michigan, evaluated the effectthat encapsulated lycopene had on patients with existing prostate cancer.The study of 30 men with prostate cancer, reported in 1999 at the annualmeeting of the American Association for Cancer Research, showed that thosepatients who took lycopene supplements had smaller tumors, which were morelikely to be confined to the prostate. The tumors in patients who consumedthe lycopene showed signs of regression and decreased malignancy.Like many antioxidants, lycopene absorbs oxygen-free radicals that candamage DNA, and is believed to be responsible for many types of cancer."This study represents the first clinical evidence that lycopenesupplements may prevent cancer," said Dr. Kucuk. "Furthermore, thefindings suggest that lycopene may not only help prevent cancer, but mayalso be useful in treating men who are already diagnosed with prostatecancer."

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