What is prostate cancer?

Prostate cancer is the most common cancer in men, and the second leading cause of cancer death among men in the U.S. More than 180,000 men in the U.S. will be diagnosed with prostate cancer this year, and more than 40,000 will die of the disease. Eighty percent of men who reach age 80 have prostate cancer.

Prostate cancer is a malignant (cancerous) tumor that usually begins in the outer part of the prostate. In most men, the cancer grows very slowly. In fact, many men with the disease will never know they had the condition. Early prostate cancer is limited to the prostate gland itself, and most patients with this type of cancer can live for years with no problems.

Prostate cancer is classified by two categories: "grade" and "stage." The size and extent of the tumor determine its stage. Early stage prostate cancer, Stages T1 and T2, are limited to the prostate gland. Stage T3 prostate cancer has advanced to tissue immediately outside the gland. Stage T4 prostate cancer has spread to other parts of the body.

What is the prostate and what does it do?

The prostate is a muscular, walnut-sized gland that surrounds part of the urethra, the tube that carries 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 main function of the prostate is to produce fluid for the semen, the milky fluid in which sperm swims. Sperm is produced in the testicles, which also make the main male hormone testosterone. During puberty, testosterone stimulates the growth and function of the prostate, and helps with the production of fluid for semen.

During sexual climax (orgasm), the muscles of the prostate tighten to push the semen through the urethra and out through the penis (ejaculation). 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, ensuring that it is only semen that is ejaculated in an orgasm.

Where is the prostate located?

The prostate is located directly beneath the bladder and in front of the rectum. The urethra passes through the prostate, so if the prostate becomes enlarged, it can keep urine or semen from passing through the urethra.

What causes prostate cancer?

Like many cancers, the cause of prostate cancer is unknown. But doctors do know that 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.

What are the symptoms of prostate cancer?

Prostate cancer, by nature, is “silent” in its early stages. Its symptoms don't appear until later, when patients may notice a need to urinate frequently, particularly at night. Prostate cancer may also cause other problems with urination, including:

  • Having trouble urinating;
  • A flow of urine that is weak or stops and starts; or,
  • Painful and burning urination.

Other symptoms may include:

  • Painful ejaculation
  • Blood in urine or semen, and,
  • Frequent pain or stiffness in the lower back, hips, or legs.

Last reviewed by a Cleveland Clinic medical professional on 07/24/2015.


  • National Cancer Institute. Prostate cancer—for patients Accessed 4/16/18.
  • American Cancer Society. Prostate cancer Accessed 4/16/18.
  • Corn P, Logothetis C. Chapter 34. Prostate Cancer. In: Kantarjian HM, Wolff RA, Koller CA. eds. The MD Anderson Manual of Medical Oncology, 2e. New York, NY: McGraw-Hill; 2011.

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