Prostate Specific Antigen (cont.)
How is PSA used to detect prostate cancer?
The PSA test is used in two distinctly different ways with
respect to detecting prostate cancer. It can be used
in men who are not known to have the disease (screening or diagnostic test) and
those who are known to have the disease (tumor marker or monitoring
test).
As a screening or diagnostic test, an abnormal result will usually
require additional testing. Levels above 4 ng/mL but less than 10
ng/mL are suspicious. However, most men who have this level of
abnormality will actually not have prostate cancer. As levels
increase above 10 ng/mL, the probability increases dramatically.
As a tumor marker or monitoring test, an abnormal result indicates
recurrence of prostate cancer following initial therapy. For example,
if the prostate gland is surgically removed (prostatectomy), and all
of the cancer is contained within the gland, then the PSA should drop
to zero. If on subsequent testing the PSA test is positive and shows
increasing levels, then not all of the cancer was successfully
removed and it has spread.
What other conditions can cause an abnormal PSA level?
Other diseases that affect the prostate gland can cause an
elevated PSA. The most frequent problem is known as benign prostatic
hypertrophy (enlargement) or hyperplasia (BPH). This condition is due
to an increase in the size of the prostate gland that typically
occurs with aging. Infection of the prostate gland (prostatitis) is
another relatively common affliction that can also cause an abnormal
elevation of PSA. Other conditions include poor blood supply to the
prostate gland, instrumentation of the urethra (drainage tube from
the bladder), urinary retention, and prostate biopsy.
What is the free PSA test?
Most of the PSA protein released into the blood becomes
attached to other blood proteins. The PSA that does not become
attached is known as free PSA and can be measured. It has been found
that the level of free PSA is decreased in men who have prostate
cancer compared to those with benign conditions. The exact level
depends upon which test the laboratory uses, but generally less than
10% free PSA is suggestive of cancer. This test is most helpful when
the usual PSA test is between 4 and 10 ng/mL.
Next: What are the limitations of the PSA test? »
- Prostate Cancer Screening - Get information on prostate cancer screening and prevention, risk factors, PSA testing, prostate exam, and other tests that screen and detect for prostate cancer. BPH has symptoms similar to prostate cancer.
- Prostatitis - Read about prostatitis, a painful infection of the prostate gland. Symptoms include fever, chills, painful urination, lower back pain, pain in the genital area, and frequent urination.
- Prostate Cancer - Learn about prostate cancer treatment, causes, signs, stages, hormone therapy, symptoms, and how to maintain good prostate health.
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