A PSA test will not tell you whether you have cancer, though it can help you and your doctors decide if you should have other tests to screen for prostate cancer.

THE PROSTATE GLAND

The prostate gland is found only in men. It is a small gland about the size of a walnut, and it enlarges with age. It surrounds the innermost end of the tube (urethra) that transports urine from the bladder through the penis.

The prostate produces a thick, white fluid called semen that mixes with sperm produced by the testicles. The prostate also makes a protein called prostate-specific antigen, or PSA. This turns semen into liquid. A small quantity of PSA flows naturally into the bloodstream.

If your prostate becomes enlarged due to inflammation or infection, or if there is a cancerous growth in the gland, greater quantities of PSA enter the bloodstream.

The growth of the cells of the prostate and the functioning of the prostate gland depend on the male sex hormone testosterone, which is produced in the testes.

THE PSA TEST

The PSA test is used to detect problems in the prostate. The test measures the volume of the PSA protein in your blood. It is normal for PSA to filter into the bloodstream. However, high levels of the protein may sometimes be a sign of prostate cancer. PSA levels may be high because of reasons other than cancer, such as infection, prolonged exercise, and ejaculation. Therefore, having high PSA levels does not means that you necessarily have prostate cancer.

There are possible advantages and drawbacks of the PSA test. While PSA tests may help detect prostate cancer at an early stage, inaccurate testing may lead to other tests that you do not need.

There is no right or wrong answer when decided whether to undergo a PSA test or not.