What is being tested?
CA-125 is a protein often found on the surface of ovarian cancer cells and in some normal tissues. It is used as a marker for ovarian cancer. However, CA-125 levels may also be high in non-cancerous conditions, including pelvic inflammatory disease, any condition causing excessive fluid in the abdomen (ascites) such as liver disease and in healthy women during pregnancy and menstruation.
How is it used?
CA-125 is used to monitor therapy during treatment for ovarian cancer. CA-125 is also used to detect whether cancer has come back after treatment is complete.
When is it requested?
Before a patient starts treatment for ovarian cancer, the doctor will measure a baseline CA-125 to compare against future measurements. During therapy, doctors use CA-125 testing, at intervals, to monitor the response to therapy. CA-125 may also be measured periodically after therapy is completed to catch any early signs of the cancer’s return.
What does the result mean?
If CA-125 levels fall during therapy, this generally indicates that the cancer is responding to treatment. If CA-125 levels rise, the cancer may not be responding to treatment. High CA-125 levels after treatment is complete may indicate that the cancer has come back.
Is there anything else I should know?
Because CA-125 can be high in many normal or non-cancerous (benign) conditions (for example, pregnancy, menstruation, endometriosis, pelvic inflammatory disease) it is not useful as a screening test for cancer.
Common questions
No, not all ovarian cancers are associated with increased levels of CA-125, especially early in the disease. Elevated levels have been found in about 80% of women with ovarian cancer.
No. CA-125 may be elevated in several other conditions and diseases. CA-125 may be high in non-cancerous conditions, including pelvic inflammatory disease, any condition causing excessive fluid in the abdomen (ascites) such as liver disease and in healthy women during pregnancy and menstruation.
Family history is a risk factor for ovarian cancer. If you have close family members who have had ovarian cancer, you are at higher risk than someone who has no family history of the disease. Make sure your doctor knows about your family medical history.
Pathology Tests Explained (PTEx) is a not-for profit group managed by a consortium of Australasian medical and scientific organisations.
With up-to-date, evidence-based information about pathology tests it is a leading trusted sources for consumers.
Information is prepared and reviewed by practising pathologists and scientists and is entirely free of any commercial influence.
