|The Truth About CA 125|
Have you seen a version of this email in your Inbox? It's the one telling the frightening cancer story of Carolyn (or Kathy or perhaps someone else) and urging you to ask your doctor for an annual CA125 blood test to screen for ovarian cancer. You may have read it over, wondering if it's truth or spam. If you checked a site such as About's Urban Legends Site, you may have seen it referred to, and concluded that the "delete file" is the place for it. However, there really is a Carolyn, and what she was trying to communicate is important. Let's meet the email's writer and find out what's real about the CA 125 blood test.
Carolyn Benivegna was a healthy 55 year old woman, who had undergone a total hysterectomy for menstrual difficulties years before. Because of a family history of breast and ovarian cancer, she decided to have her ovaries removed as well. When in 1998 she began experiencing swelling in her abdomen and changes in bowel function, she consulted a doctor who ran some tests and diagnosed Irritable Bowel Syndrome. It was through Carolyn's intuition that something had been missed that more tests were performed, including the CA 125. Ultimately, she was diagnosed with primary peritoneal cancer, which is essentially identical to epithelial ovarian cancer (the most common type of ovarian cancer).
It was during her treatment that Carolyn wrote the now-(in)famous email. "I was very upset and angry", says Carolyn, "because nobody had told me (a) that I was still at risk for this disease even after I had my ovaries removed, and (b) nobody had ever told me about the CA-125 test, even though I was a high-risk individual for ovarian cancer."
Before long, the email was spread far and wide, and is still wending its way through cyberspace, along with several variations. I've received 3 of them in the past few weeks! It seems that once something gets out through the Internet, it's pretty much unstoppable!
Now, almost three years after her diagnosis, Carolyn is going strong. She has become an educator and advocate for women on issues surrounding ovarian/primary peritoneal cancers. She has revised the original email, and would like to see the new form posted on Web sites instead of the original. She was recently interviewed for an article in the Wall Street Journal. And she has turned an email originally written out of anger and fear into an opportunity to tell others about the warning signs of Ovarian Cancer, and the steps they can take to get an early and accurate diagnosis.
What is the CA 125 Test?
The CA 125 test is a blood test that determines the level of an antigen in the blood which is known to be a tumor marker. It is commonly used to monitor the state of the disease in ovarian cancer patients, because 80-90% of women with ovarian cancer in its later stages will have signs of the antigen in their blood.
Why isn't the test commonly used as a screening test?
Unfortunately, the test is not as sensitive or specific as would be ideal. This means that there are "false positive" and "false negative" results associated with the test, and at unacceptably high rates to be used as a general screening test (as, for example, mammograms and Pap tests are used).
False Positives - There are many common conditions that can cause an elevation of CA 125 in the blood. Among them are normal ovulation, endometriosis, pelvic inflammatory disease, the first trimester of pregnancy, fibroid tumors, and other sources of inflammation in the abdominal and pelvic organs (liver disease, pancreatitis, etc). Also, cervical, endometrial, and other cancers (among them breast, colon, and lung) can inconsistently cause a rise in CA 125.
Looking at this list (which is far from complete, but covers the major conditions), one might notice that they fall roughly into two categories: conditions common in the childbearing years, and conditions you would actually want to know about if you had them. CA 125 does cause many more false positives in pre-menopausal women. But especially after menopause, a false positive for ovarian cancer might be a true positive for something else. Scientists are now at work trying to find ways to use the CA 125 test that might provide more accurate screening information.
False negatives - Another big problem with using the CA 125 for general screening is that it has an unacceptable rate of false negatives. This means that a woman can have a normal test result and still have ovarian cancer. This is especially true in the earliest stage of ovarian cancer - which is exactly when you want a screening test to work well! At least half of women with stage 1 ovarian cancer have normal levels of CA 125 in their blood.
Is CA 125 ever used for screening at this time?
Yes. Women known to be at high risk for ovarian cancer are often screened regularly, using a combination of the CA 125 test, transvaginal ultrasound, and a rectal/pelvic examination. If you have reason to think you have a high risk for ovarian cancer, you should ask your doctor about this. The most significant risk factor is having close relatives with histories of ovarian and/or breast cancer, particularly if they were younger than 50.
Is there any other test that might work for general screening?
The LPA (lysophosphitidic acid) test is showing some promise for the detection of early-stage ovarian cancer. It is still under study at this time.
What else can I do to protect myself from ovarian cancer?
First, remember that for most women (absent high risk), ovarian cancer is not a common cancer. Most of the life changes that are protective against ovarian cancer are fairly major, so they would always have to be weighed against the odds. For example, if you are trying to decide between oral contraceptives and some other form of contraception, you might want to take into consideration that oral contraceptives have a protective effect with regard to ovarian cancer. Otherwise, you might not want to go out of your way to take extra hormones. The most important things you can do are to 1) familiarize yourself with risks and well as the symptoms of ovarian cancer, and 2) get a pelvic exam (including a recto-vaginal exam) every year.
Original Article Written in April of 2001
Copyright © 2001 by Laura Dolson. All rights reserved.
The material on this page and Web site is for informational and educational purposes only, and should not substitute for medical advice. Anyone having questions about the application of information appearing here to a specific person or situation should obtain advice from a qualified physician.