What Is the Deal With the CA 125 Ovarian Cancer Test?

by Mona Saint MD

I keep getting that email that talks about the CA 125 test for ovarian cancer and to ask your doctor. I did ask my doctor and she said it really wasn’t a good test, but we didn’t have time to discuss. What are your thoughts on it? I know ovarian cancer is an awful cancer.

I get asked this excellent question by patients all the time, and I too have received that email about the CA 125 test too many times to count. The interest in diagnosing ovarian cancer early on is valid, given that it has the highest death rate of all the gynecological cancers and can be very hard to diagnose at an early stage. Fortunately, this type of cancer is not very common; the lifetime chance of developing ovarian cancer is just less than 2%.

CA 125 is a tumor marker that is found to be elevated on a blood test in many of the ovarian cancers. Unfortunately, in patients at low risk for ovarian cancer and who are premenopausal this is not a good screening test. The problem with it is that it is elevated in a lot of normal conditions including: fibroids, various times in the menstrual cycle, endometriosis, pelvic inflammatory disease, pregnancy, ovarian cysts, as well as about 20 other nongynecological conditions including heart disease, diabetes, lung disease and liver disease. About 1% of normal women have an elevated CA 125 (1). The other problem with the test is it can be normal in some patients who actually have ovarian cancer, since not all ovarian cancers make this tumor marker.

If it was a good test to do on everyone, we would check it once a year like a Pap smear and I would make sure all my family members also got it checked. Unfortunately it is not. It would cause a lot of unnecessary surgery in healthy women, including the concerning risks related to the surgery if we screened everyone. If my patients have no risk factors but absolutely want the test done,  I never say no since it is their body and their health. However, usually once I counsel them about it, most understand why it is not a good screening test.

For women who are at high risk for ovarian cancer (first degree family members with ovarian cancer), we often check a CA 125 and pelvic ultrasound once a year or so, although unfortunately this approach hasn’t shown to pick up on that many cancers and in fact still misses many cancers even in those with normal ultrasounds and CA 125’s. None of the major gynecological or cancer organizations recommend using CA 125’s for routine screening. Gynecologists do check a CA 125 in women in whom we find a concerning ovarian mass on ultrasound, especially in postmenopausal women, but this is different than routine screening.

The good news is that researchers are working on panels of blood tests that can be elevated in women with ovarian cancer, in hopes to detect it early on and improve survival rates. Some of these are becoming commercially available, and they hold great promise. Currently the best bet for ovarian cancer prevention is the BRCA genetic tests. If you have more than one family member with ovarian cancer, have family members with breast and ovarian cancer, or are Jewish with one first degree relative with ovarian cancer, I would highly recommend meeting with a genetic counselor to discuss BRCA genetic testing-to see if you carry the genes that can significantly increase your lifetime chances of having this devastating cancer. Ideally the family member with cancer should be tested but this is not often possible. If you see a genetic counselor, consider bringing sisters with you so you can all learn about your options.

Fortunately early symptoms have now been identified for ovarian cancer in hopes to detect it early and there are ways to reduce risk including using birth control pills, and we’ll talk more about these in a future issue.

References: 1) Up to Date 2009

{ 1 comment }

celeste 03.25.09 at 7:06 am

thank you for the info. I lost my aunt to this terrible disease! she did have the genetic testing done (I thought it was wonderful for her to do so for the rest of the family) and the results showed it was not genetic. I look forward to your future issue that discusses symptoms. thank you again!

Comments on this entry are closed.