CA 125 (ovarian) Test

A CA 125 test measures the amount of the protein CA 125 (cancer antigen 125) in the blood. This test may be used to monitor certain cancers during and after treatment. In some situations, the test may be used to look for early signs of ovarian cancer in people with a very high risk of the disease. A CA 125 test isn't accurate enough to use for ovarian cancer screening in general because many conditions can increase the level of this protein.