Why isn't the CA-125 test used to screen for ovarian cancer?

David A. Fishman, MD
Gynecologic Oncology
Most gynecologic oncologists use the CA-125 test for surveillance of epithelial ovarian cancer (EOC) after surgical confirmation of the diagnosis because it may be a sensitive indicator of persistent or recurrent disease. Unfortunately, CA-125 is less reliable for the detection of cancer in premenopausal women, since it is frequently elevated in noncancerous conditions, such as
pregnancy, endometriosis, uterine fibroids, liver disease, benign ovarian cysts, and in other malignancies, such as colon, uterine, fallopian, gastric and pancreatic cancer.

CA-125 screening for EOC in the general population is problematic; an elevated value accurately detects malignancy in less than 3% of women. Therefore, although it is the best available serum marker, CA-125 is not sensitive enough to warrant its use as a sole marker to screen for ovarian cancer. In fact, in a study of 110 EOC patients, using a cutoff value of 35 U/ml, the sensitivity was only 57%, while the specificity was 100%. Therefore, researchers have concluded that although serum CA-125 values alone are highly specific, they are insufficiently sensitive to recommend screening for EOC in the general population.

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