The prostate is a muscular, walnut-sized gland that surrounds part of the urethra, the tube that transports urine and sperm out of the body. A gland is a group of cells that secretes chemicals that act on or control the activity of other cells or organs.
The prostate is part of the male reproductive system. Its main job is to make seminal fluid, the milky substance that transports sperm.
Sperm is produced in the testicles, which also make the male hormone testosterone. Testosterone stimulates the growth and function of the prostate during puberty.
During sexual climax (orgasm), the muscles of the prostate contract to push semen through the urethra and out the penis. The urethra also carries urine, a waste product made by the kidneys and stored in the bladder. When the penis is erect during sexual intercourse, the flow of urine is blocked from the urethra, allowing only semen to be ejaculated at orgasm.
Where Is the Prostate Located?
The prostate is located directly beneath the bladder and in front of the rectum. Because the first portion of the urethra passes through the prostate, the passage of urine or semen through the urethra can be obstructed if the gland becomes enlarged.
What Is Prostate Cancer?
Prostate cancer is the most common cancer, excluding skin cancers, in American men. It is a malignant tumor of the prostate. In most men, the cancer grows very slowly. In fact, many men with the disease will never know they have the condition. Early prostate cancer is confined to the prostate gland itself. The majority of patients with this type of cancer can live for years with no problems.
Prostate cancer is characterized by both "grade" and "stage." The grade is given to indicate how the cancer cells look under the microscope when a biopsy is analyzed. The grade often predicts how quickly a cancer is growing and will spread -- the higher the grade, the more likely it is that the cancer will grow and spread rapidly. The size and extent of the tumor when first detected determine its stage.
What Causes Prostate Cancer?
As with many cancers, the cause of prostate cancer is unknown. But doctors do know it is more common in African-American men and men with a family history of the disease. The male sex hormone testosterone also contributes to its growth. Read more about risk factors.
How Many Men Have Prostate Cancer?
The American Cancer Society estimates that about 240,890 men in the U.S. will be diagnosed with prostate cancer this year, and approximately 33,720 will die of the disease. Overall, about one man in six will be diagnosed with prostate cancer during his lifetime, but only one man in 36 will die of this disease. About 80% of men who reach age 80 have prostate cancer.
What Is the Outlook?
While the number of men diagnosed with prostate cancer remains high, survival rates are also improving. Nearly 100% of men with common types of prostate cancer survive at least five years after their diagnosis, 91% survive at least 10 years, and 76% survive longer than 15 years.
Because prostate cancer is a slow-growing disease, many men with this disease will die from other causes before they die from prostate cancer. Evidence also indicates that many patients detect their prostate cancer at an earlier stage because of annual screening.