Prostate cancer is an important public health problem. Prostate cancer accounts for one of every three cancers among American men. Researchers are conducting studies to learn more about the causes and early detection of this common disease.

Causes and Prevention

The causes of prostate cancer are not yet understood. Researchers are looking at factors that may increase the risk of this disease. The more they can learn about these risk factors, the better the chance of finding ways to prevent and treat prostate cancer.

Studies in the United States show that prostate cancer is found mainly in men over age 55; the average age of patients at the time of diagnosis is 72. This disease is more common in black men than in white men. In fact, black men in the United States have the highest rate of prostate cancer in the world. Doctors cannot explain why one man gets prostate cancer and another does not, but they do know that no one can "catch" prostate cancer from another person. Prostate cancer is not contagious.

Some studies have shown that a man has a higher risk for prostate cancer if his father or brother has had the disease. However, researchers are uncertain why some families have a higher incidence of prostate cancer.

Scientists are studying the effects of diet. Some evidence suggests that a diet high in fat increases the risk of prostate cancer and a diet high in fruits and vegetables decreases the risk, but these links have not been proven.

Researchers have studied whether having a vasectomy increases a man's risk for prostate cancer. Some studies suggest there may be such a link, but other studies have not supported this claim.

Other studies show that farmers and workers exposed to the metal cadmium during welding, electroplating, or making batteries may have an increased risk of getting this disease. Also, workers in the rubber industry appear to develop prostate cancer more often than members of the general public. However, more research is needed to confirm these results.

Scientists are also doing studies to determine whether BPH or a sexually transmitted virus increases the risk for prostate cancer. At this time, they do not have clear evidence of increased risk in either case.

Men over age 55 are taking part in a study of finasteride (trade name Proscar^®), a drug used to treat BPH. This nationwide NCI study, called the Prostate Cancer Prevention Trial, is designed to help doctors learn whether finasteride can prevent prostate cancer. The Cancer Information Service can provide information about this study.

Detection

Researchers are studying ways to screen men for prostate cancer (check for the disease in men who have no symptoms). At this time, it is not known whether screening actually saves lives. The NCI-supported Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial is designed to show whether certain tests can detect these cancers early enough to reduce the number of deaths they cause. For prostate cancer, this trial is looking at the usefulness of screening with digital rectal exam and checking the PSA level in the blood in men ages 55 to 74. The results of this trial may change the way men are screened for prostate cancer. The Cancer Information Service can provide information about this trial.

Men should talk with their doctor about prostate cancer, the symptoms to watch for, and an appropriate schedule of checkups. The doctor's advice will be based on the risks and benefits of diagnosis and treatment, as well as a man's age, medical history, and other factors.

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