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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) is used to:
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 women who have a very high risk of ovarian cancer, such as those with BRCA gene changes. For these women, the benefits of screening may outweigh the harms.
You do not need to do anything before you have this test.
The health professional drawing blood will:
The elastic band around your upper arm may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.
There is very small chance of problems from having blood drawn from a vein.
The cancer antigen 125 (CA-125) test measures the amount of the CA-125 protein in the blood.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
Less than 35 units per milliliter (U/mL)
Less than 35 kiloUnits per liter (kU/L) (SI units)
Results of a cancer antigen 125 test can be affected by:
CitationsFischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.Other Works ConsultedChernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.Pagana KD, Pagana TJ (2010). Mosby's Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby.
Current as ofDecember 19, 2018
Author: Healthwise StaffMedical Review: Kathleen Romito, MD - Family MedicineE. Gregory Thompson, MD - Internal MedicineJimmy Ruiz, MD - Medical Oncology, Hematology
Current as of: December 19, 2018
Author: Healthwise Staff
Medical Review:Kathleen Romito, MD - Family Medicine & E. Gregory Thompson, MD - Internal Medicine & Jimmy Ruiz, MD - Medical Oncology, Hematology
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