*skips to fridge and eats edamame*

[Guest guest]

Men who eat soy and tomatoes reduce their risk of prostate cancer, study shows

Thursday, June 7, 2001

 

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Ralph deVere White, director of the UC Davis Cancer Center and chair of the

Department of Urology at the UC Davis Medical Center.

 

Men at risk of prostate cancer might want to include more tofu and soy milk

in their diets following the results of a study at the University of

California at Davis Cancer Center. Although the study was conducted with

mice, and results must be replicated with humans, researchers found that a

chemical found in soy slowed prostate cancer growth in mice and caused

prostate cancer cells to die. The soy chemical found to reduce prostate

cancer in mice is called genistein, one of two compounds in soy that belong

to a family of chemicals known as isoflavones. Isoflavones are

phytoestrogens, plant based chemicals that mimic the effects of estrogen in

the body. Researchers theorize that the prevalence of soy in Asian diets may

be one reason why men in Asia have a lower rate of prostate cancer than men

in the United States. Prostate cancer is the most common cancer among

American men.Ralph deVere White, director of the UC Davis Cancer Center and

chair of the Department of Urology at the UC Davis Medical Center, presented

the results of this study at the annual meeting of the American Urological

Association in Anaheim this week. " We've identified the mechanisms by which

genistein may work in prostate cancer, and it's consistent with other studies

of soy, " said deVere White. " While we are encouraged by these results, we

need to test genistein in patients with prostate cancer to be certain of its

effectiveness. " The American Cancer Society estimates that there will be

334,500 new cases of prostate cancer in the United States this year. Prostate

cancer is expected to kill over 40,000 American men this year.For the UC

Davis study, scientists tested a commercially made extract of genistein on

mice bred to develop prostate cancer and on metastatic prostate cancer cell

lines. In mice, genistein reduced prostate cancer tumor growth. In the tissue

culture, genistein increased the production of p21, a gene that regulates

cell growth, and it reduced the production of vascular endothelial growth

factor, a protein that helps cancer grow. These factors caused cancer cells

to die. UC Davis researchers are now evaluating the effects of genistein in

men who have been diagnosed with slow growing prostate cancer. The cancer

center intends to enroll 70 men in a pilot study to see if genistein lowers

levels of prostate specific antigen, a tumor marker for prostate cancer. Men

who have chosen not to receive treatment for prostate cancer or who have

undergone treatment and whose prostate specific antigen levels are rising

slowly are eligible to volunteer for the trial. Results will be known in a

year.It is unlikely genistein would become a stand alone treatment for

prostate cancer, said deVere White. " But we hope it could be used in

conjunction with conventional therapy or as a preventive drug, if it indeed

lowers prostate specific antigen. " Other components in foods have been found

to reduce prostate cancer. Studies now show that an all natural supplement of

lycopene, the chemical that makes tomatoes red, may help prevent and treat

prostate cancer.Omer Kucuk, M.D., professor of Medicine and Oncology, and

colleagues at the Karmanos Cancer Institute in Detroit, Michigan, evaluated

the effect that encapsulated lycopene had on patients with existing prostate

cancer. The study of 30 men with prostate cancer, reported in 1999 at the

annual meeting of the American Association for Cancer Research, showed that

those patients who took lycopene supplements had smaller tumors, which were

more likely to be confined to the prostate. The tumors in patients who

consumed the lycopene showed signs of regression and decreased malignancy.

Like many antioxidants, lycopene absorbs oxygen-free radicals that can damage

DNA, and is believed to be responsible for many types of cancer. " This study

represents the first clinical evidence that lycopene supplements may prevent

cancer, " said Dr. Kucuk. " Furthermore, the findings suggest that lycopene may

not only help prevent cancer, but may also be useful in treating men who are

already diagnosed with prostate cancer