DEAR DR. GOTT: I would like more information about the blood test CA-125 for ovarian cancer. Articles and doctors here in Topeka, Kan., insist there is no test for ovarian cancer. However, I’ve read about it and have talked to people who have had this test. Topeka is now having a Whisper Walk and awareness for ovarian cancer such as we’ve had for breast cancer, but the people putting it on still say there is no such test.
DEAR READER: CA-125 is a protein found more often in ovarian-cancer cells than in other cells, and because it enters the bloodstream, it can be measured by a blood test. The rate at which CA-125 levels increase is a more accurate method of detecting ovarian cancer than is single testing for the same purpose. Therefore, when comparing figures, it is important to be assured that the test used in each case is the same generation, same manufacturer and same type of assay.
A CA-125 provides a true positive result in about 50 percent of all stage I ovarian-cancer patients. A single test is not to be used for early detection; however, it has an 80 percent chance of returning positive results from stage II, III and IV ovarian-cancer patients.
There are a number of disorders that can cause false-positive results. They include pelvic inflammatory disease, benign ovarian cysts, endometriosis and first-trimester pregnancy. Beyond these diagnoses, almost 60 percent of people with pancreatic cancer, 70 percent of those with cirrhosis and up to 25 percent of people with other malignancies will have elevated CA-125 levels. There is a lower specificity in premenopausal women than in those who are postmenopausal.
Therefore, a CA-125 test alone is not recommended for detection but should be done serially for more accurate results. It should also be used in conjunction with a rectovaginal pelvic examination and transvaginal sonography.
To further complicate things, other tumor antigens, such as CA 15-3, CA 19-9, OVX1 and M-CSF, exist; however, only the OVX1 appears to hold diagnostic potential. There is also a tumor-marker test that measures levels of plasma lysophosphatidic acid (LPA) being developed. So stay tuned.
To provide related information, I am sending you a copy of my Health Report “Vaginal Infections and Disorders.” Other readers who would like a copy should send a self-addressed stamped No. 10 envelope and a $2 check or money order to Newsletter, P.O. Box 167, Wickliffe, OH 44092-0167. Be sure to mention the title or print an order form off my website at www.AskDrGottMD.com.
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