Ovarian Cancer Screening Tests
A number of tests have been evaluated as potential methods of screening for ovarian cancer. Screening tests with the greatest amount of clinical test data supporting their use include transvaginal ultrasound and the blood test for the serum marker CA-125. (Serum markers are substances in the blood that can be detected in blood tests.) Less information is available regarding a number of other serum markers, used alone or in combination. A newer test based on proteomics, a method which involves the evaluation of patterns of dozens to hundreds of low molecular weight proteins simultaneously, has also been recently proposed.
The CA-125 blood test measures the amount of a protein called CA-125 in the blood. Many women with ovarian cancer have high levels of CA-125. This test can be useful as a tumour marker to help guide treatment in women known to have ovarian cancer, because a high level often goes down if treatment is working. But checking CA-125 levels has not been found to be as useful as a screening test for ovarian cancer. The problem with using this test for ovarian cancer screening is that high levels of CA-125 is more often caused by common conditions such as endometriosis and pelvic inflammatory disease. Also, not everyone who has ovarian cancer has a high CA-125 level. When someone who is not known to have ovarian cancer has an abnormal CA-125 level, the doctor might repeat the test (to make sure the result is correct) and may consider ordering a transvaginal ultrasound test.
TVUS (transvaginal ultrasound) is a test that uses sound waves to look at the uterus, fallopian tubes, and ovaries by putting an ultrasound wand into the vagina. It can help find a mass (tumour) in the ovary, but it can’t actually tell if a mass is cancer or benign. When it is used for screening, most of the masses found are not cancer
Factors that increase your risk of ovarian cancer include the following:
- Older age
- Having one or more relatives with ovarian cancer
- Having abnormalities in a gene, called BRCA1 or BRCA2
- Having genes that are linked to hereditary nonpolyposis colorectal cancer (HNPCC; also called Lynch syndrome)
- Never being pregnant
- Being overweight
Some factors can reduce your risk of developing ovarian cancer, including:
- Using hormonal methods of birth control (pills, patch, vaginal ring, injection)
- Being pregnant, breastfeeding
- Having your tubes tied to prevent pregnancy
- Having your uterus or ovaries removed
Risks and benefits of ovarian cancer screening
A screening test is one that can find a disease, such as cancer, in the early stages when there are no symptoms and when the cancer is most likely to respond to treatment. An example of a common screening test is the Pap smear, which is used to detect cervical precancers and cancers.
A screening test must find most people with the condition and not mistakenly find people who do not have the condition. A test that is positive when no disease is present is termed a “false-positive” test. It is especially important to avoid having false-positive tests for ovarian cancer, since a positive screening test usually requires surgery.
Benefits — The potential benefit of ovarian cancer screening is the chance to find the cancer at a curable stage, reducing the risk of dying.
Risks — The potential risk of ovarian cancer screening is having a false-positive screening test. This might lead to unnecessary surgery for many healthy women. Surgery carries risks including anxiety, injury, costs, and time out of work, as well as a small risk of serious complications.