How accurate is ca125 test for ovarian cancer?

99% when cancer: Ca-125 is 99% accurate if an ovarian cyst or tumor happens to be cancer. The problem with this blood test is that it is very inaccurate when there is no cancer (called a false positive), sometimes up to 45%. This is why ob/gyns do not use this test as a screening test, or at patient request.

Most of the time: A tumor marker with normal is 35u, level will be elevated in ovarian cancer used as a monitoring tool for metastasis, especially advanced ovarian . Ca also elevated GI malignancies ca of tube and endometrium, besides benign conditions, like pid, pancreatitis, cirrhosis, endometriosis, fibroids, lupus etc.