CA-125 Blood Test (Ovarian Cancer) Test
This test measures the amount of a protein called CA-125 in your blood. High levels can be a sign of ovarian cancer, but other conditions can also cause high levels.
What this test measures
This test measures the amount of a protein called CA-125 (cancer antigen 125) in a sample of your blood. CA-125 is a type of tumor marker that may be made by cancer cells or normal cells in response to cancer.
What your results mean
Reference ranges vary by laboratory and by your age and sex. MedlinePlus does not publish a single normal range for this test — always read your result against the range printed on your own lab report and discuss it with your provider.
Higher-than-normal results
High CA-125 levels could be a sign of ovarian cancer, especially if you are at high risk or have a suspicious pelvic lump. However, other conditions such as endometriosis, pelvic inflammatory disease, uterine fibroids, liver disease, menstruation, or pregnancy can also cause high levels.
Frequently asked questions
What does CA-125 stand for?
CA-125 stands for cancer antigen 125.
Why is the CA-125 test most commonly used?
According to MedlinePlus, the most common use is to see if ovarian cancer treatment is working or to check if ovarian cancer has come back.
Can a normal CA-125 result rule out ovarian cancer?
No. A normal CA-125 test result does not rule out ovarian cancer because CA-125 levels may be low in early stages, and not everyone with ovarian cancer makes high levels.
What non-cancer conditions can cause high CA-125?
Non-cancer conditions include endometriosis, pelvic inflammatory disease, uterine fibroids, liver disease, menstruation, and pregnancy.
Is the CA-125 test used for routine screening?
No. MedlinePlus states that providers cannot use CA-125 to screen for ovarian cancer if you are not at high risk.
Related lab tests
Sources
- MedlinePlus: CA-125 Blood Test (Ovarian Cancer) — NIH MedlinePlus
Last updated . Information is aggregated from official public sources and is not a substitute for professional medical care.