Reasons, Preparation, Procedure & Risks Involved In a Cancer Antigen 125 Test

Submitted on March 27, 2012

A cancer antigen – 125 is a protein that is often noticed on the surface of several ovarian cancer cells. This protein is also present in small amounts in other cancers and is found in normal tissue. A cancer antigen blood test can find out the level of protein in the blood. The CA-125 is a tumor marker and can often show if the person has some sort of cancer. This test is also done to find out if the treatment for ovarian cancer is working on a patient or if the cancer has returned.

Reason for the cancer antigen 125 or CA-125 test

This test is done to check the following –

  • If the cancer treatment administered to a patient is working.
  • If the cancer has returned.
  • To check if the cancer is focussed on the ovaries.
  • Often an ultrasound is combined with a CA-125 test to see if a woman has ovarian cancer.


You don’t need to work on any special arrangements or preparations for this test.


A blood test is done to check for the antigen in the blood. For this, a healthcare professional will insert a needle in your arm and draw out some blood. It is a routine procedure and the same steps are followed as in any other blood test.

How will you feel after the test

There might be a feeling of tightness when the elastic is wrapped around your arm. Also, when the needle goes in, you’ll feel a sting. But don’t worry about pain, as all you will experience is a pinch.

Risks involved

There is very less scope for any risks in a simple blood test procedure. At the most, you’ll have a bruise in the place where the needle is inserted. You might also feel raw or tender in that area for some time. You can use a warm compress to get relief. However, if you have been taking blood-thinning medicines, then ongoing bleeding might be something that you may experience. In such a case, speak with your doctor.

Other conditions

If the value of CA-125 is high and you do not have cancer, then some of the other common related conditions that you might be checked for are: pancreatitis, liver disease, uterine fibroids, endometriosis, pelvic inflammatory disease (PID), first trimester of pregnancy, lupus, or a certain time of your menstrual cycle