Prostate cancer is the abnormal growth of cells in a man's prostate gland. The prostate gland is part of a man's reproductive system. It is, on average, a little bigger than a walnut. It is located between the base of the bladder and the beginning of the penis. It surrounds the upper part of the urethra. (The urethra carries urine from the bladder out through the penis.) The prostate makes the fluid that nourishes and carries sperm.

Prostate cancer has become the most commonly diagnosed cancer among men in the US. It usually grows slowly. Men who have it more often die from other causes before the cancer kills them. Still, prostate cancer is one of the most common causes of cancer death in American men. The prostate cancer death rate is especially high among African-American men for unknown reasons.