CA-125 is a test used to evaluate ovarian cancer treatment. CA-125 is a protein that is found more in ovarian cancer cells than in other cells. This protein enters the bloodstream and can be measured by a blood test.
There are two CA-125 tests: a first generation test and a second generation test. The second generation test is now more widely used and is generally more accurate.
Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.
Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm. 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 often used to follow women who have been diagnosed with ovarian cancer and who have previously had high CA-125 levels. In these cases, the CA-125 test is a very good tool to determine if ovarian cancer treatment is working, and whether the cancer remains in remission after treatment.
The CA-125 test may also be done if a woman has symptoms or findings on ultrasound that suggest ovarian cancer.
However, in general, the CA-125 is not a good test to screen healthy women for ovarian cancer.
Dann RB, et al. Strategies for ovarian cancer prevention. Obstet Gynecol Clin North Am. 2007;34(4):667-686.
Goonewardene TI, et al. Management of asymptomatic patients on follow-up for ovarian cancer with rising CA-125 concentrations. Lancet Oncol. 2007;8(9):813-821.
National Comprehensive Cancer Network. NCCN Practice Guidelines in Oncology: Ovarian cancer. 2009; v2.
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