CA 125 Test

1 What is a CA 125 Test?

A CA 125 test measures the quantity of protein CA 125 (cancer antigen) in your blood. A CA 125 test may be used to monitor certain cancers during and after treatment.

In some cases, a CAA 125 test can be used to look for early signs of ovarian cancer in women who have a very high risk of the disease.

A CA 125 test is not accurate enough to be used for ovarian cancer screening in all women because many noncancerous conditions can raise the CA 125 level.

Many different conditions can cause an increase in the CA 125 level including normal conditions, such as menstruation, and non-cancerous conditions such as uterine fibroids.

Certain cancers may also cause an increased level of CA 125, including ovarian, endometrial, and peritoneal and fallopian tube cancers.

2 Reasons for Procedure

You may have a CA 125 test for the following reasons:

  • To monitor cancer for treatment. If you have endometrial, ovarian, peritoneal or fallopian tube cancer, your doctor might recommend a CA 125 test on a regular basis in order to monitor your particular condition and treatment. But such monitoring has not been shown to improve the outcome for women with ovarian cancer, and it might lead to additional and unnecessary rounds of chemotherapy or other treatments.
  • T screen for ovarian cancer if you are at a high risk. If you have a strong family history of ovarian cancer or you have the BRCA1 or BRCA 2 gene mutation, your doctor may recommend a CA 125 test as an option to screen for ovarian cancer. Some doctors may recommend CA 125 testing in combination with transvaginal ultrasound every six months for women at a very high risk. However, some women with ovarian cancer may not have an increased CA 125 level. And no evidence proves that screening women with CA 125 decreases the chance of dying of ovarian cancer. A high level of CA 125 could prompt your doctor to put you through redundant and possibly harmful tests.
  • To check for cancer recurrence. Rising CA 125 levels may indicate that ovarian cancer has returned after treatment. Regular monitoring of CA 125 has not been shown to improve outcomes for women with ovarian cancer and may lead to additional and unnecessary rounds of chemotherapy or any other treatment. If your doctor has suspicions that you may have ovarian cancer or another form of cancer, he or she may recommend a biopsy to collect a sample of cells. Other tests that may be helpful in evaluating these cancers include a transvaginal or pelvic ultrasound and computerized tomography (CT).

3 Potential Risks

The CA 125 is a simple test that involves draw a blood sample from your vein located on your arm and usually carries no potential risks.

4 Preparing for your Procedure

There are no needed preparations for the CA 125 test. If your blood is being tested only for CA 125, you eat and drink normally before the test.

5 What to Expect

Here you can find out what to expect from your CA 125 test.

For a CA 125 test, a member of your health care team takes a sample of your blood by inserting a needle into a vein, which is usually located in your hand or arm.

The blood sample is then sent to a lab for analysis. You will then return to your daily activities immediately.

6 Procedure Results

The results of a CA 125 test are measured in units per milliliter (U/mL). The normal value is below 35 U/mL. If your CA 125 level turns out to be higher than normal, you may have a benign condition or the test result could mean that you have ovarian, endometrial, peritoneal or fallopian tube cancer.

You doctor may also recommend other tests and procedures in order to determine your diagnosis.

If you have a diagnosis of ovarian, endometrial, peritoneal or fallopian tube cancer, a decreasing CA 125 level is often an indication that the cancer is responding to the treatment. A rising CA 125 level may indicate a return or continued growth of cancer.

A number of normal and noncancerous conditions can lead to elevated CA 125 level, including:

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