Cancer Treatment Centers of America

CA-125 test for ovarian cancer

CA-125 test for ovarian cancer

CA-125 is a protein in the blood. High amounts of CA-125 may indicate ovarian, fallopian tube or peritoneal cancer, as well as less serious conditions, such as endometriosis or inflammation in the abdomen. We often use this test in combination with other diagnostic methods.

A CA-125 test is also often used during cancer treatment. High levels of CA-125 that begin to decline may indicate the treatment is having a positive effect. If the level instead continues to rise, your doctor may consider changing your treatment regimen. 

What is CA-125?

CA-125 refers to the amount of cancer antigen 125 in a person's blood. The protein is a biomarker, or tumor marker, that is found in greater concentration in cancer cells, particularly ovarian cancer cells.