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8/3/2019 What is CA 125
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What is CA 125?
CA 125 is a protein that is a so-called tumor marker or biomarker, which is a substance that is found in greater
concentration in tumor cells than in other cells of the body. In particular, CA 125 is present in greater
concentration inovarian cancer cells than in other cells. It was first identified in the early 1980s, and the function
of the CA 125 protein is not currently understood. CA stands for cancer antigen.
How is CA 125 measured?
CA 125 is usually measured from a blood sample. It can also be measured in fluid from the chest or abdominal
cavity. The tests currently in use are all based upon the use of an antibody that is directed against the CA 125
protein (monoclonal antibody technique).
In 1996, an improved version of the test was introduced and is sometimes denoted as CA 125 - II. The numerical
figure of the second generation test results may be higher or lower than a first generation test. When comparing
multiple test results over time, it can be important to know which method was used.
What is the normal range for CA 125?
The normal values for CA 125 may vary slightly among individual laboratories. In most laboratories, the normalvalue is less than 35 U /ml.
What does an elevated CA 125 mean, and how is the test used?
It is not possible to interpret the meaning of an abnormally high CA 125 without additional information about the
particular patient being evaluated. The reason is that blood levels of this protein can be increased in many
different benign and malignant conditions. The two most frequent situations in which CA 125 is used is to monitor
patients with a known cancer(malignancy) or as one of several tests in the workup of a patient suspected of
having a tumor.
The most common use of the test is the monitoring of women with known cancer of the ovary (ovarian cancer). In
the patient who is known to have a malignancy, such as ovarian cancer, the CA 125 level can be monitored
periodically. A decreasing level generally indicates that therapy, includingchemotherapy, has been effective,while an increasing level indicates tumor recurrence. Because of test variation, small changes are usually not
considered significant. A doubling or halving of the previous value would be important.
In the patient who is being evaluated for a pelvic mass, a CA 125 level greater than 65 is associated with
malignancy in approximately 90% of cases. However, without a demonstrable mass, the association is much
weaker.
What conditions other than ovarian cancer can cause an increased CA 125?
A number of benign conditions can cause elevations of the CA 125 level,
includingpregnancy, endometriosis, uterine fibroids(benign tumors), pancreatitis, normalmenstruation, pelvic
inflammatory disease, and liver disease. Benign tumors or cysts of the ovaries can also cause an abnormal test
result. Increases can also be seen in cancers other than ovarian cancer, including malignancies of the uterinetubes,endometrium, lung, breast, pancreas, and gastrointestinal tract.
Is CA 125 testing useful as a cancer screening test?
Although CA 125 is a useful test in monitoring women who are being treated for ovarian cancer, a single CA 125
test is not considered to be a useful screening test for cancer. Some women with ovarian cancer (up to 20%)
never have elevated CA 125 levels, while most women who do have elevated CA 125 levels do not have cancer.
In fact, because CA 125 can be elevated in so many non-cancerous conditions, only about 3% of women with
elevated CA 125 levels have ovarian cancer.
Cancer Antigen 125 (CA-125)A 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.
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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 hasreturned.
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 treatmentis 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-125levels 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 anultrasound scan may be used to test women who have a high chance of
ovarian cancer. Women have a high risk of ovarian cancer if they have a family his tory 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 severalminutes.
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.
Cancer Antigen 125 (CA-125)
Results
The cancer antigen 125 (CA-125) test measures the amount of the CA-125 protein in the blood.
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The normal values listed here-called a reference range-are just a guide. These ranges vary from lab to lab, and your labmay 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.
Cancer antigen 125 normal values Normal: Less than 35 units per milliliter (U/mL) Less than 35 kiloUnits per liter (kU/L)(SI units)
High values
Conditions other than cancer that can cause high CA-125 values include:
o Pelvic inflammatory disease (PID). o Endometriosis.
o Uterine fibroids.
o Liver disease (such as hepatitis or cirrhosis).
o Pancreatitis.
o The first trimester of pregnancy.
o Certain times during the menstrual cycle. o Lupus.
Types of cancer that can cause high CA-125 values include:
o Ovarian cancer or cancer of the fallopian tubes or endometrium. Most women with an ovarian cancer lump that can be
felt in the pelvic area have CA-125 values higher than 65 U/mL.
o Cancer of the pancreas, stomach, esophagus, liver, breast, colon, or lung.
o Cancers that have spread to the lining of the abdomen (peritoneum), includinglymphoma. These types of cancersusually occur along with the buildup of fluid in the abdomen (ascites).
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.
Belly 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 enoughproof to show that this test works to find ovarian cancer early.
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