Can Prostate Cancer Be Prevented?

Because the exact cause of prostate cancer is not known, at this time it is not possible to prevent most cases of the disease. Many risk factors such as age, race, and family history cannot be controlled.

Current information on prostate cancer risk factors, however, suggests that some cases might be prevented.

Diet

You may be able to reduce your risk of prostate cancer by changing the way you eat.

The American Cancer Society recommends 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. Bread, cereals, grain products, 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 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. But other studies have found that vitamin E supplements have no impact on cancer risk and may increase risk for some kinds of heart diseases. Selenium, a mineral, may also lower risk. On the other hand, vitamin A 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 Selenium and Vitamin E Cancer Prevention Trial (SELECT) is a large clinical trial designed to find out whether either selenium or vitamin E supplements (or both) can help protect against prostate cancer. The study opened in 2001 and has enrolled more than 32,000 men. The results of the study will probably not be available for several years.

Medications

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

Researchers have been interested in finding out whether a drug called finasteride (Proscar), which is already used to treat benign prostatic hyperplasia (BPH), can reduce prostate cancer risk. Finasteride prevents the body from making a certain potent androgen (male hormone).

The Prostate Cancer Prevention Trial (PCPT) was a study that enrolled more than 18,000 men to learn whether finasteride reduced the risk of prostate cancer. Each man in the study was randomly assigned to take either finasteride or a placebo (sugar pill) each day for 7 years. 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 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 continuing to watch these men to see if these cancers really do grow and spread more quickly.

The men taking finasteride were more likely to have sexual side effects such as lowered sexual desire and episodes of impotence than those taking placebo. But they were less likely to have urinary problems such as trouble urinating and leaking urine (incontinence).

At this time, it is not clear 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.