See also: Ask the Pros: What conditions other than ovarian cancer can cause an elevated CA-125?
Cancer antigen 125 is a substance that is produced in the fallopian tubes, uterus, cervix, and the lining the lining of the chest and abdominal cavities (the pleura and the peritoneum). The CA 125 test measures a sugar protein that may be released when cells are inflamed or damaged. CA 125 levels are usually measured by a blood test, but can also be detected in fluid from the abdominal and chest cavities. Levels under 35 kU/ml are considered normal.
Ovarian cancer cells may produce an excess of these protein molecules, as may some other cancers, including cancer of the fallopian tube or endometrial cancer (cancer of the lining of the uterus). Occasionally an elevated CA 125 test indicates other benign activity not associated with cancer, such as menstruation, pregnancy, or endometriosis. However, in early stage ovarian cancer, this molecule may not necessarily be released. Thus, the test is not an effective screening test.
The CA 125 test may be used diagnostically in combination with other tests such as vaginal ultrasound, and can also be used to monitor the progress of patients with cancer: increasing levels may indicate a recurrence, while decreasing levels may indicate a response to treatment.
- "Ovarian Cancer and You" Supplemental to Current Oncology Journal, vol. 5, supp 2. Nov 98.
- FocusOnCancer.com, "CA 125" http://www.focusoncancer.com/script/main/Art.asp?li=MNI&ArticleKey=8099
Cyndee, Pennsylvania, USA: My doctor told me that many things can cause the CA 125 to increase - an infection, a cold etc. What I was told is that they watch to see if there is a rising trend in the CA 125 levels. For example, say yours was twelve last time, and this time it is 21. If it goes down next time, they won't worry about it. If you have another CA 125 sample done and it increases again, they may want to do some tests. If you are concerned, you should speak with your doctor about it and get a professional opinion.
What I might do if I were you is call my gynecologic oncologist and ask what the next plan of action is. Personally, I believe my doctors and I are a team, and our goal is to see me through the "cancer experience" and make my quality of life the best it can possibly be.
Another option may be to request a second opinion, or have a PET scan done. In any case I would be proactive about this and keep pushing until I was satisfied with their answers; after all, it is your body and your life!
Janet M., Pennsylvania, USA: My CA 125 at the time of surgery was over 27,000. Treatments of Taxol® and carboplatin brought it down to around 200 before the chemotherapy stopped being effective. I had six months off of treatment, and my CA 125 went up to over 1700. After four infusions of Doxil®, my CA 125 level was down to 29. The "magic 35" is the guideline for those who have never had cancer. For those of us with the misfortune to have cancer, the number used as a baseline is much lower. Any continuous rise could be significant.