What is CA-125?
This is a protein produced by some kinds of cancer cells, including most ovarian cancer cells. It is called a cancer marker because it is produced by cancer cells and is released into the bloodstream, so that it can be detected with a simple blood test.

Is the CA-125 test accurate for detecting early ovarian cancer?
The CA-125 blood test is not adequate for early detection of ovarian cancer when used as a single screening tool. It would only correctly identify about 50% of stage I ovarian cancers. It would detect about 80% of stage II, III, and IV ovarian cancers. Twenty percent of patients with ovarian cancer will not show an abnormal CA-125 level.

There are several non-cancerous conditions that can cause elevated levels of CA-125. Examples are endometriosis, ovarian cysts, pregnancy, pelvic infection, and liver disease. Also, other cancers beside ovarian cancer can cause an elevated CA-125 level (colon cancer, pancreatic cancer and others). Because of all these limitations, the CA-125 test is not recommended for use as a single screening method for detecting early ovarian cancer. The chance of having a false positive result is very high, particularly for women under age 50.

If the CA-125 is combined with transvaginal pelvic ultrasound it gives greater accuracy for detecting early ovarian cancer. In addition, serial CA-125 testing increases the accuracy of the test. Serial testing involves having several blood tests over a period of time to observe whether or not the level increases.

What if the CA-125 level is abnormal?
An elevated level of CA-125 could be a false positive (in which case we may not ever know why it is elevated) caused by a non-cancerous ovarian cyst, ovarian cancer or some other type of cancer. Once a positive test is obtained, surgery may be considered. In some cases women will undergo removal of the ovaries, finding them to be completely normal. Removal of the ovaries does not completely eliminate the risk of developing ovarian cancer in the future, but it reduces the risk by 90% or more.

What if the CA-125 level is normal?
A normal level could be a true negative, or a false negative (meaning there is a cancer that is not producing this protein). The next step depends on the patient’s personal and family health history, and the results of other testing such as a pelvic ultrasound. Generally screening is performed yearly, but may be recommended more often for some individuals.

Where do I have this test drawn and how am I notified of results?
You may have your blood drawn at Women’s Wellness Center at the time of your pre-consult visit. You will be notified of your results at your cancer risk assessment consultation.

How often do I need to have the CA-125 blood test?
For those interested in ovarian cancer screening, this blood test should be done every 6-12 months, depending on individual risk factors. In some cases, more frequent testing is recommended.