Diet

While the results of research studies are not yet clear, you may be able to reduce your risk of prostate cancer by changing the way you eat.

The American Cancer Society recommends choosing foods and beverages in amounts that help achieve and maintain a healthy weight, eating a variety of healthful foods with an emphasis on plant sources, and limiting your intake of red meats, especially high-fat or processed meats. Eat 5 or more servings of fruits and vegetables each day. Whole-grain breads, cereals, rice, pasta, and beans are also recommended. These guidelines on nutrition may also lower the risk for some other types of cancer, as well as other health problems.

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. Some earlier studies suggested lycopenes may help lower prostate cancer risk, although a more recent study found no link between blood levels of lycopene and risk of prostate cancer. Research in this area continues.

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. But other studies have found that vitamin E supplements have no impact on cancer risk, and larger doses may increase risk for some kinds of heart diseases. Selenium, a mineral, may also lower risk. On the other hand, beta-carotene supplements may actually raise prostate cancer risk. Taking any supplements can have risks and benefits. Before starting vitamins or other supplements, you should talk with your doctor.

The possible effects of selenium and vitamin E on prostate cancer risk are now being studied in the Selenium and Vitamin E Cancer Prevention Trial (SELECT). This large clinical trial is under way, but the results will probably not be available for several years.

Several studies are now looking at the possible effects of soy proteins (called isoflavones) on prostate cancer risk. The results of these studies are not yet available.

Medicines

Some drugs may also help reduce the risk of prostate cancer.

Finasteride (Proscar) is a drug already used to treat benign prostatic hyperplasia (BPH). It works by preventing the body from making a certain potent androgen (male hormone).

A large clinical trial (the Prostate Cancer Prevention Trial, or PCPT) tested taking finasteride versus a placebo (sugar pill) each day for 7 years. At the end of the study, men taking finasteride were less likely to have prostate cancer than those getting the placebo. But the cancers that did develop in the men taking finasteride looked like they were more likely to grow and spread. The reason for this is not known. Researchers are still watching these men to see if these cancers really do grow and spread more quickly.

Finasteride was more likely to cause sexual side effects such as lowered sexual desire and impotence. But it seemed to help with urinary problems such as trouble urinating and leaking urine (incontinence).

At this time, not all doctors agree whether taking finasteride to prevent prostate cancer is a good thing. Men thinking about this should discuss it with their doctors. The results of the PCPT will become clearer over the next few years.

Other drugs that may help prevent prostate cancer are now being tested in clinical trials. These include anti-inflammatory drugs such as celecoxib and drugs that affect hormone levels such as toremifene.