The CA 125 test determines the amount of CA 125 (cancer antigen 125) in the blood. CA 125 is a tumor marker. The substance is made by normal cells but also by tumor cells. Cells in an ovarian tumor produce an extra amount of CA 125, which is why CA 125 is used as a marker for ovarian cancer.
WHEN TO TEST?
- Determine the amount of CA 125 in patients with (increased risk of) ovarian cancer. The amount of CA 125 can be used to check whether a treatment for ovarian cancer is effective. It can also be determined whether a previously treated tumor returns in the ovaries.
- Before treatment for ovarian cancer is started, the amount of CA 125 in the blood is measured. This is the baseline value. In the further course of treatment, CA 125 will still have a be measured number of times. If the value is lower, the treatment is effective.