Study suggests ways to prevent prostate cancer

Apr 11 2004

Current information on prostate cancer risk factors suggests that some cases might be prevented. One possible risk factor that can be changed is diet. You may be able to reduce your risk of prostate cancer by changing the way you eat.

Tomatoes (raw, cooked, or in tomato products such as sauces or ketchup), pink grapefruit, and watermelon are rich in lycopenes. These vitamin-like substances are antioxidants that help prevent damage to DNA and may help lower prostate cancer risk.

Taking vitamin or mineral supplements may affect your prostate cancer risk, but this is not yet clear. Some studies suggest that taking 50 milligrams (or 400 International Units) of vitamin E daily can lower risk. Although other studies found vitamin E to be of no benefit, reasonable doses of this vitamin have no significant side effects and are not expensive. Selenium, a mineral, may also lower risk. On the other hand, vitamin A supplements may actually increase prostate cancer risk. If you are unsure about whether you should take vitamins or other supplements, talk with your doctor.

The Selenium and Vitamin E Cancer Prevention Trial (SELECT) is a large clinical trial designed to determine if these 2 supplements can protect against prostate cancer. The study opened in 2001 and will enroll 32,000 men. Unfortunately, results of the study will probably not be available until 2013. Men interested in participating in this study may call the National Cancer Institute at 1-800-4-CANCER (1-800-422-6237) or visit the NCI website.

Some drugs may also help reduce the risk of prostate cancer. Researchers have been interested in determining whether a drug called finasteride (Proscar), which is already used to treat benign prostatic hyperplasia (BPH), can reduce prostate cancer risk. Finasteride prevents the prostate from being affected by certain androgens (male hormones). Androgens are known to be important in promoting the growth of normal and cancerous prostate cells and may play a part in the development of prostate cancers.

The Prostate Cancer Prevention Trial was a study that enrolled more than 18,000 men to determine whether finasteride reduced the risk of developing prostate cancer. Each man in the study was randomly assigned to take a pill each day for 7 years. The pill consisted either of finasteride or a placebo, but the men didn’t know which pill they were taking.

At the end of the study, the men taking finasteride were about 25% less likely to have developed prostate cancer than those getting the placebo. But the men taking finasteride who did develop prostate cancer were more likely to have cancers that appeared to be of a higher grade when viewed under a microscope. These cancers may be more likely to grow and spread. The reason for the higher grade cancers is not known. The study researchers are continuing to watch these men to see if these cancers truly are more aggressive.

The men taking finasteride were more likely to experience sexual side effects, such as decreased sexual desire and episodes of impotence, than those taking placebo. But they were less likely to have urinary problems, such as difficulty urinating and inability to hold urine in (incontinence).

Each man considering taking finasteride to reduce his risk of developing prostate cancer should consider the results of this study carefully, and should discuss the possible pros and cons with his doctor when deciding on an appropriate course of action.