CA 125 Test
At a Glance
Why Get Tested?
To monitor treatment for ovarian cancer
When to Get Tested?
Before starting therapy for ovarian cancer or if at high risk for developing ovarian cancer, and at intervals during and after treatment
Sample Required?
A blood sample taken from a vein in the arm
The Test Sample
What is being tested?
CA 125 is a protein often found on the surface of ovarian cancer cells and in some normal tissues. It is used as a marker for ovarian cancer. However, CA 125 levels may also be high in other types of non-cancerous conditions, including menstruation, pregnancy, and pelvic inflammatory disease.
How is the sample collected for testing?
Blood is taken from a vein in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
The Test
How is it used?
CA 125 is mainly used to monitor therapy during treatment for ovarian cancer. CA 125 is also used to detect whether cancer has come back after treatment is complete. This test is sometimes used to follow women who at high-risk because they have a family history of ovarian cancer but who do not yet have the disease. CA 125 is also recommended together with pelvic ultrasonography in women aged over 50 years who have persistent, continuous or worsening unexplained tummy pain or problem with urination and in whom a doctor is concerned after examining the tummy.
When is it requested?
Before a patient starts treatment for ovarian cancer, the doctor will measure CA 125 to be able to compare it with future measurements. During therapy, doctors use CA 125 testing, at intervals, to follow the response to therapy. CA 125 may also be measured several times after therapy is completed to catch any early signs of the cancer’s return.
What does the test result mean?
If CA 125 levels fall during therapy, this generally indicates that the cancer is responding to treatment. If CA 125 levels rise, the cancer may not be responding to treatment. High CA 125 levels after treatment is complete may indicate that the cancer has come back.
Is there anything else I should know?
Common Questions
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Article Sources
NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
