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If a blood test shows an elevated CA-125, it can be suggestive of a number of different things, depending on other information about the patient that will have been collected during an examination. Levels of this protein in the blood are most commonly checked in connection with ovarian cancer treatment or diagnosis, and elevated levels can mean that a patient has ovarian cancer or that a cancer is recurring. However, false positives do happen. The CA-125 test is not intended to be used as a standalone diagnostic tool.
CA-125 is a protein that is produced primarily in cancer cells. It is associated most commonly with ovarian cancer, although other cancers can cause an elevated CA-125 as well. In addition, other malignant or benign conditions ranging from endometriosis to a regular menstrual period can also be linked with higher CA-125 levels. Test results are most meaningful in women with a history of ovarian cancer or women with a high risk of cancer.
If an elevated CA-125 is connected with significant clinical findings on an ultrasound exam, symptoms such as pain and abnormal bleeding, and a high risk of cancer, it can mean that a woman has ovarian cancer. For women who are in treatment for cancer, elevated results mean that the cancer is not responding to treatment and it is time to discuss other treatment options.
False positives can happen for a number of reasons. If a patient appears otherwise healthy and the test shows elevated CA-125, a repeat test may be ordered. It is also possible to have a false negative. Some women with ovarian cancer do not have an elevated CA-125 and thus will show no signs of cancer on the blood test. Because of the risks of false positives and negatives it is important to combine the test with other diagnostic options.
A second generation test, the CA-125II, may be preferred by some care providers. If doctors plan to compare test results, as may be done while a patient is in treatment for cancer or is being evaluated to check for recurrences of the cancer, they will use the same test type to avoid confusion. If a patient has a history of CA-125II tests, for example, she should be given another second generation test so that the results can be fairly and accurately compared. Lowered results between tests mean that a cancer is responding to treatment or has gone into remission.