Is CA-125 a screening test for ovarian cancer?

There is no screening test that will tell you if you have ovarian cancer or not.  Doctors use CA 125 to help in diagnosis and in monitoring the treatment of women with ovarian cancer.  It helps in  evaluating the likelihood that a suspicious ovarian cyst is cancer or not.  Only when the cyst or ovary is removed and examined, you can be sure it is cancer or not.  This test cannot be used to tell if you have ovarian cancer because the CA-125 marker may be elevated in conditions other than ovarian cancer.  The test is not specific enough to use for this purpose.  Other conditions that will cause the test to be elevated include endometriosis, fibroids, and diseases of the bowel.  Even smoking has been shown to cause an elevation of CA-125.