CA-125 Blood Test (Ovarian Cancer)

CA-125 Blood Test (Ovarian Cancer)

CA-125 blood test is a useful marker for diagnosing and monitoring ovarian cancer. The CA-125 blood test measures the levels of a protein in the blood called cancer antigen 125 (CA-125). High levels of CA-125 can be indicative of the presence of ovarian cancer. However, other conditions can also cause an increase in CA-125 levels. CA-125 is not 100% sensitive or specific for cancer and should only be one of many diagnostic tools used in the evaluation of a patient.


No advance preparation is typically needed for the CA-125 blood test.


A healthcare professional will take a blood sample from a vein in the arm. The blood sample will be sent to a laboratory for analysis.


CA-125 levels are typically measured either in U/mL or KU/L. One unit is equivalent to one milliliter of blood. Normal CA-125 levels are typically 35 units or less but may vary from lab to lab.


The CA-125 test is a safe procedure with minimal risks. There may be some bruising or slight pain at the injection site.

Why the Test is Performed

CA-125 blood tests are used to help detect and diagnose ovarian cancer, as well as to monitor the response to cancer treatment. The test may also be used to help find out if a relapse of the cancer is occurring.

When the Test is Performed

The CA-125 test may be performed if the doctor suspects that the patient has ovarian cancer or if ovarian cancer is already known or suspected. The results of the blood test may help determine the extent of the cancer, monitor the effectiveness of treatment, and identify the possibility of a relapse.