CA-125

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CA-125 is a protein that is more prevalent in ovarian cancer cells than in other cells. This protein enters the blood stream and can be measured by a blood test. There are two CA-125 tests, a first and second generation test. The second generation test is now more widely used and is generally more accurate.

Blood is drawn from a vein on the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to fill with blood.

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

No preparation is necessary.

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

The test is most appropriately used to follow women who have already been diagnosed with ovarian cancer. In these cases, the CA-125 is a very good indicator of whether a patient is responding to treatment for her cancer, and whether a patient remains in remission after treatment. In general, the CA-125 is not a good test to screen healthy women for ovarian cancer.

Review Date: 12/01/2005
Reviewed By: Sharon Roseanne Thompson, M.D., M.P.H., Department of Obstetrics & Gynecology, Brigham and Women's Hospital, Boston, MA. Review provided by VeriMed Healthcare Network.