What Is It?

Prostate cancer is the uncontrolled growth of abnormal cells in the prostate gland, a gland near the base of the penis that produces part of the fluid in semen.

Prostate cancer is common, but not always dangerous. When cells in the prostate become cancerous (malignant), they first form small islands of cancer that are confined to the prostate. This localized form of cancer affects about one-third of men as they grow older. In many cases, it takes years, or even decades, for this limited cancer to grow beyond the prostate gland's tough outer capsule.

If cancer grows beyond the prostate gland, it may invade surrounding parts of the bladder and urethra, causing problems with urination. The cancer also may spread to nearby lymph nodes, or to the bones, liver or rectum. Prostate cancer that has spread to lymph nodes or other organs usually cannot be cured, although they often can be kept under control for a number of years with medical therapy.

Although researchers still do not know the exact cause of prostate cancer, they have identified several factors that increase the risk of getting this disease:

• Older age - Microscopic islands of cancer can be seen in the prostates of about 30% of men at age 60, and 50% to 70% at age 80. Overall, about three out of four cases of prostate cancer are diagnosed in men over age 65.

• African-American heritage - African-American men are more likely to get prostate cancer than other men, and the cancer often is more advanced when it is diagnosed. In the United States, an African-American man is twice as likely to die of prostate cancer as a white man.

• 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 with no family history of the illness. Genetic (inherited) factors may be responsible for approximately half of the rare prostate cancers that develop in men under the age of 55.

• Lifestyle factors - Men who eat high fat diets, especially animal fats, have an increased risk of prostate cancer.