Cancer antigen 125 testing

Cancer antigen 125 (CA 125) is a tumor marker. This protein may be found in elevated levels in the blood, urine or body tissues of people who have certain types of cancer -- particularly ovarian cancer.


Purpose
Tumor markers can provide clinically useful information to help you and your doctor choose treatment options, make changes in therapy or decide to stop treatment.

Indications
Blood tests to measure CA 125 levels can help monitor treatment of ovarian cancer, as well as screen for possible recurrence once treatment is complete. Generally, less CA 125 is produced as a tumor shrinks. Levels may rise if the tumor recurs.
Annual CA 125 testing may be recommended if you have hereditary ovarian cancer syndrome. Talk to your doctor about the need for annual testing if you have other risk factors, such as a history of fertility drug use or a mother, sister or daughter with ovarian cancer.

Your doctor may also recommend other screening tests to help make a diagnosis, including a pelvic exam and a transvaginal ultrasound (using sound waves through the vagina to create images of the uterus and ovaries).


Patient preparation
No special preparation is necessary.

Procedure
CA 125 testing is a simple blood test. Results are typically available within three to seven days. Any reading above 35 U/mL (units per millimeter) is considered elevated.

Postprocedure care
After your blood is drawn, pressure will be applied to the site and a small adhesive bandage will be put in place.

Benefits
Measuring CA 125 levels is an effective way to monitor the response to treatment for ovarian cancer, as well as monitor for recurrences. The cost and risks are minimal.

Risks
Because many ovarian cancers don't produce CA 125, false-negative results are possible. Sometimes, the amount of CA 125 released is too small to be detected. Elevated levels of CA 125 can also indicate many conditions other than ovarian cancer, including:
menstruation or early pregnancy
endometriosis (when the tissue that lines the uterus grows outside the uterus)
pelvic inflammatory disease (an infection of the female reproductive organs)
peritonitis (inflammation of the membrane lining the abdominal cavity)
pancreatitis (inflammation of the pancreas, the gland that produces some of the enzymes the body needs to digest food)
liver disease
any condition that causes inflammation of the tissues that surround the lungs and line the chest cavity
other types of cancer

Considerations
Most health experts agree routine CA 125 testing and transvaginal ultrasounds are unnecessary for women who have a low risk of ovarian cancer. The significant number of false-positive results can lead to unneccessary surgical procedures.
Certain factors may reduce the risk of ovarian cancer, including:

pregnancy (The more children you deliver, the smaller the risk.)
breastfeeding
using oral contraceptives
tubal ligation (a type of female sterilization)
hysterectomy (surgical removal of the uterus)
oophorectomy (surgical removal of both ovaries)