Cancer Antigen 125 (CA-125) Test
Test Overview
Cancer antigen 125 (CA-125) is a protein found on the surface of many ovarian cancer cells. It also can be found in other cancers and in small amounts in normal tissue. A CA-125 test measures the amount of this protein in the blood.
CA-125 is used as a tumor marker, which means the test can help show if some types of cancer are present. Most often, the CA-125 test is used to check how well treatment for ovarian cancer is working or to see if ovarian cancer has returned.
The test for cancer antigen 125 (CA-125) may be used to:
- Check to see if treatment for cancer is working. If the level of CA-125 is going down, it usually means that the treatment is working.
- Follow up on a lump or mass found in the pelvic area.
- Check to see if ovarian cancer has returned.
- Check to see if the ovary is the main site of cancer. If a doctor has found a cancer that has spread to another part of the body (metastatic cancer), the doctor may do a CA-125 test to find out where the cancer started. High levels of CA-125 are a strong sign that the cancer started in the ovary. But other types of cancer can increase CA-125 levels too.
Experts do not recommend using the CA-125 test as a screening test for ovarian cancer because it often has false-positive results that can lead to unneeded surgery. But some doctors may recommend the CA-125 test and a transvaginal ultrasound for those who have a very high risk of ovarian cancer, such as those with BRCA gene changes. For these people, the benefits of screening may outweigh the harms.
When a blood sample is taken, you may feel nothing at all from the needle. Or you might feel a quick sting or pinch.
There is very little chance of having a problem from this test. When a blood sample is taken, a small bruise may form at the site.
Normal
Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you.
High values
- Conditions other than cancer that can cause high CA-125 values may include:
- Liver disease (such as hepatitis or cirrhosis).
- Pancreatitis.
- The first trimester of pregnancy.
- Types of cancer that can cause high CA-125 values include:
- Ovarian cancer or cancer of the fallopian tubes or endometrium.
- Cancer of the pancreas, liver, breast, colon, or lung.
- Cancers that have spread to the lining of the abdomen (peritoneum).
Current as of: July 31, 2024
Author: Ignite Healthwise, LLC Staff
Clinical Review Board
All Ignite Healthwise, LLC education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.
