Elevated CA 125 level: A sign of ovarian cancer?

Does an elevated CA 125 level always indicate ovarian cancer? Or can it mean something else?

- Carol / New York

Mayo Clinic oncologist Timothy Moynihan, M.D., and colleagues answer select questions from readers.

Answer

Women with ovarian cancer often have an elevated level of cancer antigen 125 (CA 125). But an elevated CA 125 level doesn't mean you have ovarian cancer. Many other conditions also can cause an elevated CA 125 level, including:

Endometriosis
Pancreatitis
Pregnancy
Normal menstruation
Pelvic inflammatory disease

Also, some women with ovarian cancer never have an elevated CA 125 level. Because of these limitations, this test isn't useful as a routine screening for ovarian cancer.

CA 125 readings are primarily used to assess how ovarian cancer is responding to treatment. In women receiving chemotherapy for ovarian cancer, a decreasing CA 125 level often indicates that the cancer is responding to treatment. A rising level may indicate a return or continued growth of the cancer.

If you have an elevated CA 125 level but haven't been diagnosed with cancer, your doctor may recommend further testing to look for the cause.