Cancer Antigen 125 (CA125) is a protein which is produced by cancer cells and which can be raised in cancers of the ovary, lung, breast, pancreas and gastrointestinal tract. As CA125 is also produced by normal cells it is important to know your base level and monitor regularly so that any change can be picked up early.
There is no national screening test for cancer of the ovary. This blood test cancer marker is raised in many cases of ovarian cancer and in some cases of endometrial cancer. It can also be raised in other conditions which are not cancerous, so care is needed in evaluating a positive result. Recent studies suggest that monitoring CA-125 for change is a much more reliable way of diagnosing cancer than a single result.
A very high level could be indicative of cancer whereas slightly raised levels may have many causes. Other conditions that cause inflammation in the pelvic area can cause CA125 to be elevated such as pregnancy, pelvic inflammatory disease, mensturation and endometriosis.
This blood test can be raised in ovarian cancer, cancer of the womb (endometrium) and some other cancers (pancreas, stomach, colon, rectum, breast).
In women who have a strong family history of ovarian or breast cancer, this test can be used regularly to try and help detect cancers in their earliest stages.
CA-125 is mostly used as a monitoring tool during treatment for ovarian cancer and to detect whether cancer has come back after treatment is complete. This check is also useful to test and monitor high-risk women who have a family history of ovarian cancer but who do not yet have the disease.
A raised level is not necessarily a sign of cancer, just as a low level does not guarantee that cancer is not present. Elevated CA125 can be caused by anything that causes inflammation in the pelvic region including menstruation, endometriosis, pregnancy and pelvic inflammatory disease. However, we recommend that all raised levels are investigated further.
This blood test is for women who have a strong family history of ovarian cancer or who are worried about unexplained symptoms. This test can be reassuring if it comes back normal but is never definite that a small cancer is not present. A high level would mean that further tests might be advisable but does not mean you defintitely have cancer. This test is also for women who wish to monitor their CA-125 for any change which might indicate ovarian cancer.