PSA - PROSTATIC SPECIFIC ANTIGEN :

Several years ago, a substance was discovered in the blood
normally produced by the prostate gland (the male reproductive
gland at the base of the bladder which produces the ejaculate
during orgasm.) This substance, known as the prostatic specific
antigen (PSA), is normally produced by the prostate in a small
amount. During disease states, the prostate releases more of this
into the blood stream and can be detected through a blood test. The
disease states which produces an elevation include injury,
infection, and most importantly, cancer. As such, this blood test has
been introduced to aid urologists in rendering care to male patients
in an attempt to detect prostate cancer at its earliest possible stage,
and thereby hopefully, making the cancer more amenable to
curative therapies.

The prostatic specific antigen should not be considered as a
"screening test" in that it cannot stand alone in the detection of
prostate cancer. Rather, the prostatic specific antigen is an
additional tool with a history and physical examination most
importantly including the digital rectal exam in evaluating male
patients, specifically to determine whether or not prostate cancer is
present.

The normal range for the laboratory which we use for prostatic
specific antigen (PSA) is between 0 - 4.0. Values falling within this
range are considered normal and are not indicative of diseased
states. Prostate cancer can exist in patients with normal PSA
values; therefore, the rectal examination is important and is not
replaced by this blood test. Values of the PSA greater than 4 and
less than 10 are considered in an equivocal range. Values elevated
to this extent can be elevated for a variety of reasons. Occasionally,
rarely, the rectal examination itself can elevate the prostatic
specific antigen. Recent prostatic infection, injury, and even
perhaps sexual activity can cause the elevation to be in this range.
Prostate cancer itself can also cause an elevation into the range of
between 4 and 10. Values greater than 10 are significant, in that
many of these values are indicative of a prostate cancer.

When patients have elevated prostatic specific antigen values and a
normal rectal examination, the first thing that is done is that the
prostatic specific antigen blood test is repeated. Laboratory errors
can occur, and before proceeding to more invasive testing, a simple
repeat of the value is indicated. If the repeated value is elevated, a
discussion with the physician will occur as to what options to take
next. The options on a confirmed elevated prostatic specific antigen
include:  (1) Careful observation with a repeat of the prostatic
specific antigen several weeks to months later or (2) Obtaining a
transrectal ultrasound, and if indicated, biopsy of the prostate.

If option (1) is chosen, it is very important for the patient to take
seriously his obligation to return to the urologist for a repeat
prostatic specific antigen blood test and rectal examination. Option
(2) involves the insertion of a probe into the rectum to visualize the
prostate with ultrasonic waves, similar to sonar or radar. No
radiation is used during this test. The transrectal ultrasound can
visualize the prostate to determine if any abnormal areas exist. This
technology, while not being precise enough to be a screen or
replace the digital rectal examination and prostatic specific antigen,
will occasionally detect areas of abnormality which can be biopsied.

Hopefully, this explanation will serve to characterize what the PSA
is and how it is used as a part of the comprehensive urologic
evaluation for early detection of prostate cancer. If you have any
questions, please write them  down and ask them, as understanding
will greatly reduce anxiety and promote a partnership between the
physician and the patient in health care.


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