Health A-Z

Medical Content Created by the Faculty of the
Harvard Medical School

Prostate Cancer

What Is It?

Prostate cancer results from the uncontrolled growth of abnormal cells in the prostate gland. This gland produces part of the fluid in semen. It is located below the bladder and in front of the rectum, near the base of the penis.

Prostate cancer is one of the most commonly diagnosed cancers in American men. Many other men have the disease, but have not been diagnosed. This is because prostate cancer has few symptoms early on.

Prostate cancer is common, but it is not always dangerous. This is because it usually grows very slowly. It affects older men; the average age at diagnosis is 70. And it's usually diagnosed before it causes any symptoms. Also, these men often have other illnesses which may be more important to treat than a cancer that doesn't cause symptoms.

When cells in the prostate become cancerous (malignant), they clump together, forming small "islands" of cancer in the prostate. In many cases, it takes years, even decades, for this localized cancer to spread beyond the prostate. And many of these cancers may never spread.

Researchers do not know the exact cause of prostate cancer. But they have identified several factors that raise a man's risk of the disease. These include:

• Age. Autopsy studies of men who died of other causes have found that about three-quarters or more of them have some degree of prostate cancer by age 80. These men didn't know they had prostate cancer.

• Race. African American men are more likely to get prostate cancer than other men—and to be diagnosed when the cancer is at a more advanced stage. They are also more than twice as likely to die of the disease as white men and about five times more likely to die of it than Asian Americans.

• Family history. If a man's father or brother has been diagnosed with prostate cancer, his cancer risk is two to three times higher than a man who doesn't have family members with the disease. Researchers have identified several genetic defects that may be more common in men who develop prostate cancer. But over all, most experts say that inherited defects cause a relatively small number of cancers.

• Lifestyle. Men who eat a lot of red meat or high-fat dairy products seem to have a higher risk of prostate cancer. There is little evidence that being overweight increases the risk of prostate cancer. However, obese men are more likely to die of the disease than men at a healthy weight.