Ovarian cancer test (CA125)
Among Australian women, ovarian cancer is the 8th most common type of cancer diagnosed, and the 6th most common cause of cancer death. The risk of developing ovarian cancer increases with age, with about 80 per cent of women diagnosed being older than 50 years.
Symptoms of ovarian cancer
Ovarian cancer often causes vague symptoms, which can make the diagnosis difficult in the early stages of disease. Some of the symptoms associated with ovarian cancer include:
- pelvic pain or discomfort;
- abdominal bloating, swelling or fullness;
- indigestion, nausea and loss of appetite;
- changes in bowel habits; and
- fatigue.
What is the ovarian cancer (CA125) test?
The ovarian cancer (CA125) test is a blood test that can detect a type of protein called CA125. CA125 is made by the body in response to different conditions, and can be produced by ovarian cancer cells. Many women with ovarian cancer have an increased amount of CA125 in their blood.
Can the CA125 test be used to diagnose ovarian cancer?
A CA125 blood test is just one of the tests that may be used to help diagnose ovarian cancer. If you have symptoms that you are concerned about, your doctor will first take a history of your symptoms and perform a physical examination. Your doctor may then order an ultrasound or CT scan of your abdomen and pelvis to look for any evidence of an ovarian tumour, as well as a CA125 blood test.
If an ultrasound or CT scan shows that you have a cyst or tumour on one (or both) of your ovaries, the CA125 test can help determine whether the growth is malignant (cancerous) or benign (non-cancerous). An elevated level of CA125 makes a diagnosis of ovarian cancer more likely.
Is there any preparation needed for the CA125 test?
A CA125 test is a simple blood test — a small sample of blood will be taken from a vein in your arm and then sent to a laboratory for analysis. There is nothing that you need to do beforehand to prepare for this test.
Is a high level of CA125 always a sign of ovarian cancer?
An elevated CA125 does not necessarily mean you have ovarian cancer. There are many other conditions that can cause your CA125 level to go up, including:
- endometriosis;
- menstruation;
- fibroids;
- benign ovarian cysts;
- pregnancy;
- pelvic inflammatory disease;
- liver disease; and
- pancreatitis (inflammation of the pancreas).
Can a normal CA125 test result rule out ovarian cancer?
A normal CA125 test cannot be used to rule out ovarian cancer. Some women with ovarian tumours never have an elevated CA125, and about half of women with early-stage tumours have a CA125 level in the normal range. So it's possible to have ovarian cancer and a normal CA125 result. For this reason, doctors generally order an ultrasound or CT scan at the same time as the blood test, to check for any evidence of ovarian cancer.
What else can the CA125 test be used for?
Women who are being treated for ovarian cancer sometimes have their CA125 levels checked periodically to measure their response to their cancer treatments. A decreasing CA125 level can indicate that the cancer is responding to treatment, whereas an increasing CA125 may indicate continued cancer growth.
Can the CA125 test be used to screen for ovarian cancer in healthy women without symptoms?
Screening tests are tests done on people without symptoms in order to diagnose a disease early, while it is still at a curable stage. Some examples of screening tests currently used include mammograms for breast cancer and Pap smears for cervical cancer.
Screening tests must be sensitive (able to reliably detect the disease in its early stages), as well as specific for the condition being tested. The CA125 test alone is not useful as a screening test for ovarian cancer, because it is not sensitive or specific enough. In fact, there are currently no accepted methods of population screening for early detection of ovarian cancer.
Last Reviewed: 28 July 2008
