How Accurate Is a CA-125 Test for Detecting Ovarian Cancer?

According to Johns Hopkins Pathology, the CA-125 test should not be used alone to detect ovarian cancer. Instead it should be used in conjuction with transvaginal sonography and rectovaginal pelvic examination for greater accuracy since combining detection methods lowers the number of false positive results.

The CA-125 test only returns a true positive result for about 50% of Stage I ovarian cancer patients and has an 80% chance of returning true positive results from stage II, III, and IV ovarian cancer patients.