Test Overview
Cancer antigen 125 (CA-125) is a
protein found on the surface of many
ovarian cancer cells. It also can be found in other
cancers and in small amounts in normal tissue. A CA-125 test measures the
amount of this protein in the blood.
CA-125 is used as a tumor
marker, which means the test can help show if some types of cancer are present.
Most often, the CA-125 test is used to check how well treatment for ovarian
cancer is working or to see if ovarian cancer has returned.
Why It Is Done
The test for cancer antigen 125
(CA-125) is used to:
- Check to see if treatment for cancer is
working. If the level of CA-125 is going down, it usually means that the
treatment is working.
- Check to see if ovarian cancer has
returned.
- Check to see if the ovary is the main site of cancer in a
woman. If a doctor has found a cancer that has spread to another part of the
body (metastatic cancer), he or she may do a CA-125 test to find out where the
cancer started. High levels of CA-125 are a strong sign that the cancer started
in the ovary. But other types of cancer can increase CA-125 levels too.
The CA-125 test is not recommended as a screening test for
ovarian cancer at this time because it often has
false-positive results. But the CA-125 test and an
ultrasound scan may be used to test women who have a
high chance of developing ovarian cancer. Women have a high risk of getting ovarian cancer if they
have a family history of ovarian cancer or certain changes (mutations) in their
DNA (BRCA1 or BRCA2).
How To Prepare
You do not need to do anything before
you have this test.
How It Is Done
The health professional drawing blood
will:
- Wrap an elastic band around your upper arm to
stop the flow of blood. This makes the veins below the band larger so it is
easier to put a needle into the vein.
- Clean the needle site with
alcohol.
- Put the needle into the vein. More than one needle stick
may be needed.
- Attach a tube to the needle to fill it with
blood.
- Remove the band from your arm when enough blood is
collected.
- Put a gauze pad or cotton ball over the needle site as
the needle is removed.
- Put pressure to the site and then put on a
bandage.
How It Feels
The elastic band around your upper arm
may feel tight. You may feel nothing at all from the needle, or you may feel a
quick sting or pinch.
Risks
There is very small chance of problems from
having blood drawn from a vein.
- You may get a small bruise at the site. You
can lower your chance of bruising by putting pressure on the site for several
minutes.
- In rare cases, the vein may become swollen after the blood
sample is taken. This condition is called phlebitis. You can use a warm
compress several times a day to treat this.
- Ongoing bleeding can be
a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and
other blood-thinning medicines can also make bleeding more likely. If you have
bleeding or clotting problems, or if you take blood-thinning medicine, tell
your health professional before your blood is drawn.
Results
The cancer antigen 125 (CA-125) test
measures the amount of the CA-125
protein in the blood.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what’s normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
High values
- Conditions other than cancer that can cause
high CA-125 values include:
- Types of cancer that can cause high CA-125
values include:
What Affects the Test
Results of a cancer antigen 125
test can be affected by:
- Medicines used to treat cancer.
- A
recent
radioactive scan, such as a
bone scan.
- Abdominal surgery. The CA-125 test
should be done at least 3 weeks after surgery.
What To Think About
- The cancer antigen 125 (CA-125) test cannot
tell the difference between a cancerous (malignant) or noncancerous (benign)
ovarian lump.
- The test for CA-125 may also be done on body fluids
(other than blood) taken from the chest or stomach area.
- High
values of CA-125 in a woman who has been treated for ovarian cancer may mean
that the cancer has returned. Often the high CA-125 level is found many months
before the return of cancer can be found in another way.
- Studies
are being done to see if CA-125 can be used as a screening test for ovarian
cancer. So far, there is not enough proof to show that this test works to find
ovarian cancer early.
References
Citations
- Fischbach FT, Dunning MB III, eds. (2009).
Manual of Laboratory and Diagnostic Tests, 8th ed.
Philadelphia: Lippincott Williams and Wilkins.
Other Works Consulted
- Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis:
Saunders.
- Fischbach FT, Dunning MB III, eds. (2009).
Manual of Laboratory and Diagnostic Tests, 8th ed.
Philadelphia: Lippincott Williams and Wilkins.
- Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby.
Credits
| By | Healthwise Staff |
|---|
| Primary Medical Reviewer | Anne C. Poinier, MD - Internal Medicine |
|---|
| Specialist Medical Reviewer | Thomas M. Bailey, MD - Family Medicine |
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| Last Revised | May 6, 2011 |
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Last Revised:
May 6, 2011
Fischbach FT, Dunning MB III, eds. (2009).
Manual of Laboratory and Diagnostic Tests, 8th ed.
Philadelphia: Lippincott Williams and Wilkins.