Cancer antigen 125 (ca-125) test

The test for cancer antigen 125 (CA-125) may be used to:

• Check to see if treatment for cancer is working. If the level of CA-125 is going down, it usually means that the treatment is working.
• Follow up on a lump or mass found in the pelvic area.
• Check to see if ovarian cancer has returned.
• Check to see if the ovary is the main site of cancer. If a doctor has found a cancer that has spread to another part of the body (metastatic cancer), the doctor may do a CA-125 test to find out where the cancer started. High levels of CA-125 are a strong sign that the cancer started in the ovary. But other types of cancer can increase CA-125 levels too.

Experts do not recommend using the CA-125 test as a screening test for ovarian cancer because it often hasfalse-positive resultsthat can lead to unneeded surgery. But some doctors may recommend the CA-125 test and atransvaginal ultrasoundfor those who have a very high risk of ovarian cancer, such as those with BRCA gene changes. For these people, the benefits of screening may outweigh the harms.

• A health professional uses a needle to take a blood sample, usually from the arm.

In general, there's nothing you have to do before this test, unless your doctor tells you to.

Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you.

• Conditions other than cancer that can cause high CA-125 values may include:
  • Liver disease (such ashepatitisorcirrhosis).
  • Pancreatitis.
  • The firsttrimesterof pregnancy.
• Types of cancer that can cause high CA-125 values include:
  • Ovarian cancer or cancer of thefallopian tubesorendometrium.
  • Cancer of thepancreas, liver, breast, colon, or lung.
  • Cancers that have spread to the lining of the abdomen (peritoneum).