- Cancer 101: Cancer Explained
- Guide to Breast Cancer
- Skin Cancer Risks
- Patient Comments: CA 125 - Testing Experience
- Patient Comments: Ca 125 - Results
- What is CA 125? What is a tumor marker?
- How is CA 125 measured?
- What is the normal range for CA 125?
- What does an elevated CA 125 level indicate, and how is the CA 125 test used?
- What conditions other than ovarian cancer can cause an increased CA 125?
- Is CA 125 testing useful as a cancer screening test?
- How much does the CA 125 test cost? Does insurance cover CA 125 testing?
Quick GuideOvarian Cancer Symptoms, Signs, Stages
What does an elevated CA 125 level indicate, and how is the CA 125 test used?
It is not possible to interpret the meaning of an abnormally high CA 125 without additional information about the particular patient being evaluated. The reason is that blood levels of this protein can be increased in many different benign and malignant conditions, and an elevated level does not mean that cancer is present. CA 125 is used most often to monitor patients with a known cancer (malignancy) or as one of several tests in the workup of a patient suspected of having a tumor.
The most common use of the test is the monitoring of people with a known cancer that elevates CA 125 level, such as cancer of the ovary. Around 75% to 85% of women with epithelial cancer of the ovary will have an elevated CA 125 level. In the patient who is known to have a malignancy, such as ovarian cancer, the CA 125 level can be monitored periodically. A decreasing level generally indicates that therapy, including chemotherapy, has been effective, while an increasing level indicates tumor recurrence. Because of normal test variation, small changes are usually not considered significant. A doubling or halving of the previous value would be important.
In the patient who is being evaluated for a pelvic mass, a CA 125 level greater than 65 is associated with malignancy in approximately 90% of cases. However, without a demonstrable mass, the association is much weaker.