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CA-125

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Also known as: CA 125 Tumor Marker
Formal name: Cancer Antigen 125
Related tests: Tumor Markers, BRCA-1 and BRCA-2, HE4 (Human Epididymis Protein)

The Test Sample

What is being tested?

The Cancer Antigen 125 (CA-125) test measures the amount of CA-125 in the blood. CA-125 is a protein that is present on the surface of most, but not all, ovarian cancer cells. This makes the test useful as a tumor marker in specific circumstances.

Significantly elevated concentrations of CA-125 may be present in the blood of a woman who has ovarian cancer. Small quantities of CA-125 are produced by normal tissues throughout the body and by some other cancers. Levels in the blood may be moderately elevated with a variety of non-cancerous conditions, including menstruation, pregnancy, and pelvic inflammatory disease.

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into 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.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.