CA-125 is a protein found 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.
CA-125 levels are also often monitored during cancer treatment. High levels of CA-125 that begin to decline may indicate that the treatment is having an effect. If the level instead continues to rise, your doctor may consider changing your treatment regimen.