Men with family history of prostate cancer accurately predict higher risk, UMHS study finds

04/01/04

Nearly one-third report using supplements to boost prostate health

ANN ARBOR, Mich. -- When a man is diagnosed with prostate cancer, his brothers are twice as likely to develop the disease as well, often at an earlier age.

New research finds these brothers are aware of their increased risk and many have taken vitamins or supplements to improve their health. The research is reported in two papers from the University of Michigan Health System.

Men participating in the research study said they felt they had a 50 percent chance of developing prostate cancer within their lifetime, and more than half of the 111 men surveyed said they were at least somewhat concerned about developing the disease. Lifetime risk for men with one first-degree relative with prostate cancer is about 56 percent, suggesting that the men surveyed were accurately assessing their risk. Results of the study will be published in the April 1 issue of Cancer.

In a related study, researchers asked the same group of men about their use of complementary and alternative medicine. More than half said they were currently taking at least one vitamin or supplement and 30 percent were using a type of complementary medicine linked to prostate health or prostate cancer prevention. Results of that study were published in the February issue of Urology.

"These findings suggest our educational programs are working," says study author David Wood, M.D., professor of urology at U-M Medical School. "The information is out there and these people understand they're at risk."

Researchers contacted 111 men whose brothers were diagnosed with prostate cancer. The men were selected from U-M's Prostate Cancer Genetics Project, a large family-based study of inherited forms of prostate cancer led by Kathleen Cooney, M.D., associate professor of internal medicine and urology at U-M Medical School and senior author on these studies. Participants completed a computer-assisted telephone survey about risk perception, screening behavior and use of complementary and alternative medicines. The men were asked about all CAM use and specifically about vitamins and supplements linked to prostate health.

The men surveyed were more concerned about lifetime risk of prostate cancer than their short-term risk of developing the disease in the next 10 years. Younger brothers of men with prostate cancer estimated their risk higher than did older brothers. Younger brothers were also nearly four times more likely to report using complementary or alternative medicine associated with prostate health.

"The men who had an older brother with prostate cancer thought they were more at risk, but in reality the older brothers of men with prostate cancer are more at risk. The risk of prostate cancer increases dramatically with age, with 70 percent of cases diagnosed after age 65," says Wood, a member of the Michigan Urology Center at UMHS.

CAM use was higher among men who expressed more concern about being diagnosed with prostate cancer in their lifetime. About 69 percent of men surveyed reported using CAM's at some point and 55 percent said they currently took at least one vitamin or supplement.

Almost 30 percent of all men surveyed said they used vitamins and supplements associated with prostate health or possible cancer preventative properties, including beta carotene, finasteride, flaxseed oil, green tea, magnesium, male hormones, saw palmetto, selenium, soy, vitamin A, vitamin C, vitamin E and zinc. The most commonly used CAMs were saw palmetto, selenium, vitamin C, vitamin E and zinc.

"There is evidence to suggest that the CAMs specifically mentioned in our paper may reduce risk of prostate cancer. However, we cannot say with any certainty that use of any of these CAMs will ultimately prevent prostate cancer since many of these agents have not been tested in formal clinical trials," says lead author Jennifer Beebe-Dimmer, M.P.H., Ph.D., a research fellow in the Department of Urology at the U-M Comprehensive Cancer Center.

Further, Beebe-Dimmer notes, herbal supplements are not monitored by the FDA, leaving open the question of exactly how much of a substance someone actually gets from taking it. Supplement use can also interfere with some medications, so it's important to tell your doctor about any CAMs.

Despite the possible risks, the study authors say the use of CAMs by men at high risk of prostate cancer indicates that these men are actively seeking ways to prevent the disease.

To prevent prostate cancer, doctors recommend a healthy diet low in saturated fats and high in fruits and vegetables and regular physical activity. In addition, men should receive an annual PSA screening beginning at age 50, or at age 40 for men at high risk.

In addition to Cooney, Beebe-Dimmer and Wood, authors on both studies include Stephen B. Gruber, M.D., Ph.D., from the U-M departments of Internal Medicine, Human Genetics and Epidemiology and Kimberly A. Zuhlke from the U-M Department of Internal Medicine. Additional authors on the Cancer paper are Doug M. Chilson and Gina B. Claeys, both from Internal Medicine. Additional authors on the Urology paper are Julie A. Douglas, Ph.D., Department of Human Genetics, and Joseph D. Bonner, Caroline Mohai and Cassandra Shepherd, all from Internal Medicine.

Source: Eurekalert & others

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