Cancer Antigen (CA) 125 Test
About the CA-125 Test
CA-125 is a substance found in the blood called a glycoprotein (a sugar associated protein) that can be measured by a simple blood test. CA-125 is considered an important tumor marker for epithelial ovarian cancer.
What Your CA-125 Level Means
Elevated CA-125 levels do not always indicate ovarian cancer, and levels can misrepresent a biological state. For instance, CA-125 can be absent when disease is present, or levels can be high when no disease or malignant disease exists.
More than 90% of advanced ovarian cancer patients have CA-125 levels above 30 U/mL. However, many women without cancer may experience elevated CA-125 levels. A CA-125 level of 35 units is generally considered to be the cutoff point for indicating presence of disease. Ninety-nine percent of healthy women have values less than 35 units.
CA-125 is used throughout the course of chemotherapy to monitor or assess treatment effectiveness. CA-125 levels are often used in conjunction with other tools to monitor treatments and the effectiveness of treatments. While CA-125 can help monitor treatment, it is not the only way to determine if treatment is effective. It is important to also look at your symptoms and for the physician to look at the images from your scans.
In some cases, CA-125 levels may remain the same or go up even if the treatment is working. Most physicians will try to use the change in numbers over time to monitor rather than a single test result. Certain studies have shown that it can take up to 3 months for a rise in CA-125 to be reflective of the progression of the disease.
Tracking CA-125 Levels with Your Doctor
It is important not to measure the effectiveness of your treatment by a single CA-125 test. A rise in CA-125 does not necessarily mean that your current treatment isn’t working. Remember that a change in CA-125 levels may be due to a normal variation in your body or in the lab testing. Work with your healthcare team to understand what tests are being used to evaluate your progress.
