Tumor biomarkers CA-125, CA15-3 and CA19-9

A tumor marker is defined as a biomarker that is often elevated by the presence of cancer and this can be found in body tissues, blood and urine. Generally, there are a large number of different tumor markers, each one is indicative of a specific disease process, these biomarkers are instrumental in oncology departments in order to detect the presence of cancer.

Cancer antigen 125 (CA-125)

CA-125 is a protein that can be present in majority of ovarian cancer cells, it is secreted into the blood stream and therefore can be measured. However, it is also found in many other non-cancerous conditions too.

CA-125 blood levels can be elevated as a result of ovarian cancer and many other cancers (for example: stomach, pancreatic, lung, breast, uterine, fallopian tube and colorectal). It is recommended to perform a CA-125 test if there is a suspect that there may be cancer, to find out if a specific cancer treatment is working or not and to find out if there is a recurrence of cancer after treatment. The CA-125 test can be a simple blood test that can measure the amount of CA-125 protein which is present in the blood. There are usually no special preparation required, a sample of blood can be taken from the vein of the arm by inserting a needle. However, one must be aware of false positive results which may be due to increase in CA-125 blood levels because of other non-cancerous conditions (for example: menstruation, pregnancy, uterine fibroids, pelvic inflammatory disease, non-cancerous ovarian cysts and endometriosis). An increase in CA-125 value can be the result of both cancers and non-cancerous conditions.

Cancer antigen 15-3 (CA15-3)

CA15-3 is a protein that is produced by many different cells, in particular breast cancer cells that has spread to other parts of the body (metastatic breast cancer). This protein is also transported through the blood, making it easy to measure. The levels of CA15-3 protein is found to be elevated in majority of women that have breast cancer. However, in some cases cancer cells don’t over produce this antigen. It is often not possible to measure CA15-3 at the early stage of breast cancer since the levels of this protein are barely above the normal levels at this stage. If the breast cancer has spread to other parts of the body (metastasised), then further tests such as HER2 status and hormone receptor testing are also required in addition to the CA15-3 test. The levels of CA15-3 are usually higher than normal in people with cancer of the pancreas, lungs, prostate and ovary but breast cancer patients display the highest levels. Also, non-cancerous conditions such as: pelvic inflammatory disease, liver disease and endometriosis can increase CA15-3, however, in these cases they only go so high and do not keep climbing over time. As a general rule, the greater the level of CA15-3 found in blood samples, then the more cancer that is present within the body. It is found that the levels are at it greatest when the breast cancer has spread to the liver, the bones or even both.

Carbohydrate antigen 19-9 (CA19-9)

CA19-9 is a protein that is present on the surface of specific cancer cells. There is also evidence to indicate that it may be released into the blood after it is shed from cancer cells. CA19-9 is a main tumor marker for the following cancers: some types of pancreatic cancers, stomach, liver, lung, bile duct, breast, colorectal, uterine and ovarian. The highest levels of this antigen can be found in individuals having advanced pancreatic cancer. In majority of cases the levels of CA19-9 are not high during the early stages of this disease. This antigen is usually measured using a blood test, in order to assess if a person is responding to treatment and to see if the pancreatic cancer is still growing or has recurred following treatment. However, it is possible to experience higher than normal blood levels of this antigen in people with non-cancerous conditions or in normal healthy individuals. Some of the common non-cancerous conditions include: cystic fibrosis, liver diseases (e.g. hepatitis or cirrhosis), inflammation of gallbladder or pancreas and some disorders of the kidney, lung or gastrointestinal tract.

Whilst tumor markers are often not always effective in the diagnosis of cancer, they play an important role determining a prognosis and planning therapy.

BioSupply is a specialist provider of immunoassay and diagnostic kits.