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The prostate-specific
antigen test (PSA
test) has become one of the standard
screening tools for prostate
cancer. A high PSA
level or a rising PSA
density are usually the first indications
of prostate cancer. Prostate specific antigen is an
enzyme that the body uses to turn semen that has congealed
after ejaculation back into the liquid. Some of the
prostate-specific antigen will naturally enter the blood
stream. A doctor who is using the PSA test to screen
for prostate cancer will use the prostate-specific antigen
as a tumor marker. A tumor, or the body in response
to a tumor, will produce a tumor marker. In the case
of the prostate gland, a swollen prostate will produce
a higher PSA level simply because it is bigger. A high
PSA score does not necessarily indicate prostate cancer,
but problems such as Benign Prostatic Hyperplasia (BPH)
or prostatitis.
To understand the prostate-specific
antigen test, patients must familiarize themselves with
nanograms,
milliliters, PSA density, and PSA velocity. A nanogram
is one thousand-millionth of a gram. PSA density refers
to the nanograms of prostate-specific antigen per milliliter.
PSA density is written: ng/mL. The PSA velocity measures
how quickly the PSA density rises. An increase of density
between yearly tests, for example from 0.4 ng/mL to
4.0 ng/mL, measures the velocity of a rising PSA level.
The prostate-specific antigen test
has been a useful tool in determining whether or not
someone has prostate cancer. The acceptable limit for
men of all ages is 4.0 ng/mL.
Some doctors criticize the PSA test’s
ability to accurately screen for prostate cancer at
all. Prostate-specific antigen levels increase due to
the enlargement of the prostate gland that accompanies
age. Some doctors believe that the PSA test indicates
only that the prostate gland has enlarged, not that
a malignant tumor has caused the enlargement. While
they do not believe that the PSA test should be discontinued,
some researchers feel that a high PSA score should not
be immediate grounds for a prostate
biopsy.
We have already mentioned that factors
besides prostate cancer may also raise the PSA score.
Besides BPH and prostatitis,
orgasm also has been shown to raise the prostate-specific
antigen level as much as ten percent. Men receiving
the PSA screening, therefore, may want to avoid sexual
intercourse or masturbation before the test. Any activity
that stimulates the prostate gland, including bicycling
or motorcycle riding, can increase a PSA level. Orgasm
and ejaculation or prostate-stimulating activities do
not contribute to prostate cancer or prostate disease.
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