Testing for Ca 125

November 12, 2012

Testing for Ca 125

Ca 125 testing can be done to determine the presence of cancer cells. It is currently specifically used to find ovarian cancer cells.

Ca 125 is a cancer antigen, a protein found at elevated levels in most ovarian cancer cells as well as some other cancers and, in small amounts, normal tissue. Ca 125 is produced on the surface of the affected cells and released into the blood stream. The test for this cancer antigen measures the amount of the specific protein in the blood.

The test

Generally speaking the Ca 125 test is used to monitor the treatment and progression of ovarian cancer. If the levels of the antigen are going down then this indicates that the treatment program is working, the same test can also determine if the cancer has returned. The Ca 125 test can also confirm whether the ovary is the main cancer site in a woman, but is not currently recommended as a screening tool for ovarian cancer.

Combining this test with an ultrasound scan may be beneficial in diagnosing those women with high risk factors for developing ovarian cancer – such as those with certain DNA changes or those with a family history of the disease.

A simple test

The Ca 125 test is a straightforward, low-risk, blood test requiring no special preparation or after care. The level of cancer antigen 125 may also be measured using fluid drawn from the chest or abdominal cavity.


The hoped for results of this test will be values of less than 35 units per millilitre.

Other causes of elevated Ca125

There are several other medical conditions which may cause an elevated Ca125 level, these include

  • Pelvic inflammatory disease

  • Endometriosis

  • Uterine fibroids

  • Liver or pancreatic disease

  • Early pregnancy

  • Lupus

  • Variations often occur during the menstrual cycle

Ovarian cancer

There are several types of identified ovarian cancer the exact cause of which remains unknown. There are, however, some known risk factors including age and family history. Ovarian cancer is much more common in women over the age of 55; who have a family history of the disease and/or who have never been pregnant. Most of the ovarian growths found in women under the age of thirty are found to be fluid filled cysts which are totally benign. At present there are no routine screening tests for ovarian cancer and the vagueness of its symptoms makes diagnosis difficult.

Symptoms may include -

  • Swelling of the abdomen

  • Feeling of pressure or pain in the abdominal area

  • Urinary frequency and urgency

  • Pain in the back and the legs

  • Unusual vaginal bleeding

  • Rapidly feeling full

Not just ovarian cancer

Ovarian cancer is not the only cancer which may cause higher levels of Ca 125, but, for women who have a noticeable ovarian cancer lump in their pelvic area the levels of this cancer antigen may be higher than 65 units per millilitres. Other cancers which give an elevated reading include -

  • Cancer of the fallopian tubes or endometrium

  • Cancer in the pancreas, stomach, oesophagus, liver, breast, colon, and lung

  • Cancers which have spread to the peritoneum -including lymphoma. These types of cancers often have an associated build up of fluid in the abdomen.

Other factors affecting the test

Factors which may affect the outcome of the test for cancer antigen 125 include -

  • Medication used in the treatment of cancer

  • Recent radioactive scans

  • Recent surgery – particularly involving the stomach


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