Prostate Specific Antigen
WHAT IS PSA?
PSA stands for “Prostate Specific Antigen” and it is a blood
test used to screen for prostate cancer. You may now be asking what is
an antigen? An antigen is a biological term for a substance that stimulates
an individual to make antibodies. The prostate is a small gland which
is located below the bladder and is found only in men. The prostate’s
function is to make seminal fluid that is ejaculated along with sperm
during intercourse. The most important thing about PSA is that this protein
is unique and is essentially only made by the prostate. No other tissue
in the body can make PSA in any significant quantity.
WHAT CAUSES PSA TO RISE?
All prostates make PSA but the normal prostate holds onto most of its PSA
and lets very little leak into the bloodstream. The PSA blood test measures
the small amount that leaks out. Any prostate abnormality allows more of
the PSA to enter the blood stream. Prostate cancer causes the most leakage,
but prostate infection (prostatitis), inflammation, or even just benign
enlargement (which most men experience as they age) can all raise the PSA.
Even a rectal exam, or ejaculation can cause a temporary small rise in PSA.
A biopsy of the prostate ( a simple procedure done in the Urologist’s
office ) can tell which of these problems exists.
WHAT IS A NORMAL PSA?
It depends on your age, and your doctor can tell you on each case. If you
are forty five years old your PSA should not exceed 2.5, however, if you
are seventy eight, it may be as high as 6.5 and still be normal. A PSA value
greater than 10 is very suspicious for prostate cancer. Urologists often
use a more refined “free-ratio” PSA in cases ofborderline abnormalities
to increase the accuracy of prostate cancer detection.
WHO NEEDS A PSA?
Although not all experts agree, the American Cancer Society and the American
Urological Association recommend PSA testing every year starting at age
50 (in conjunction with a rectal examination). For patients at higher risk
(African-Americans, or family members with prostate cancer) screening should
start at age forty. The test is generally not as useful in screening for
prostate cancer in men over the age of 75.
WHY IS IT IMPORTANT?
Prostate cancer does not cause symptoms until it has spread. PSA identifies
cancer in patients before it can be detected with a rectal exam and before
it spreads. Early diagnosis is the key to aggressive treatment.
HOW DO I GET A PSA TEST?
Just ask your doctor or call your Urologist.
