Serial CA-125 Treatment Monitoring
Currently there is one main blood test, a “tumor marker”, which can be useful in epithelial ovarian cancer follow-up. It is called the CA-125. This test basically measures a microscopic substance which is produced by the tumor and breaks off, circulating in the bloodstream. It is not elevated in every patient with ovarian cancer, and can be falsely elevated in people who have no diagnosis of cancer. That is why it is not very good for ovarian cancer screening.However, when an ovarian cancer is definitely diagnosed by biopsy and the CA125 is elevated at the initial diagnosis,levels can be followed as a rough measure of treatment effect. In general, for the best possible prognosis, it should drop to normal (<35) within three cycles of chemotherapy.
Some patients have a mild elevation in CA125 (35-200 or so). This may be due to inflammation from the cancer which is not due to the cancer producing CA125 by itself. It can even be due to the inflammation from surgery, if the blood test is done too soon after surgery (within two months). So, in cases of low elevation, it may not be a good marker for you to gauge treatment results. There are also other “tumor markers” which may be used, but the CA125, despite its limitations, is the most reliable in ovarian cancer.
Overall, if the CA125 was elevated at the beginning of treatment, if it is going down, the treatment should continue. If it is going up or stuck at an elevated level, it may be time to re-evaluate options. This re-revaluation can be accomplished by various types of scans, usually ultrasound, CT or PET scans. If it is obvious that the cancer is growing despite treatment, it is time to consider other chemo or biological therapies.
