Measurements of tumour marker levels can be useful – when used along with x-rays or other tests – in the detection and diagnosis of some types of cancer. However, measurements of tumour marker levels alone are not sufficient to diagnose cancer for the following reasons:
- Tumour marker levels can be elevated in people with benign conditions.
- Tumour marker levels are not elevated in every person with cancer – especially in the early stages of the disease.
- Many tumour markers are not specific to a particular type of cancer; the level of a tumour marker can be raised by more than one type of cancer.
- Conclusions based on tumor marker tests are seldom based on one test result but on a series of test results, called serial measurements. A series of increasing or decreasing values is more significant than a single value.
A tumor marker associated with liver, testicular, and ovarian cancer. Non-cancerous conditions that can cause elevated AFP levels include benign liver conditions, such as cirrhosis or hepatitis; ataxia telangiectasia; Wiscott-Aldrich syndrome; and pregnancy.
Carcinoembryonic Antigen (CEA)
CEA is normally found in small amounts in the blood of most healthy people, but may become elevated in people who have cancer or some benign conditions. The primary use of CEA is in monitoring colorectal cancer, especially when the disease has spread. CEA is also used after treatment to check for recurrence of colorectal cancer. However, a wide variety of other cancers can produce elevated levels of this tumour marker, including melanoma, lymphoma, and cancers of the breast, lung, pancreas, stomach, cervix, bladder, kidney, thyroid, liver and ovary.
Elevated CEA levels can also occur in patients with non-cancerous conditions, including inflammatory bowel disease, pancreatitis, and liver disease. Tobacco use can also contribute to higher-than-normal levels of CEA.
Initially found in colorectal cancer patients, CA 19-9 has also been identified in patients with pancreatic, stomach, and bile duct cancer. Researchers have discovered that, in those who have pancreatic cancer, higher levels of CA 19-9 tend to be associated with more advanced disease. Non-cancerous conditions that may elevate CA 19-9 levels include gallstones, pancreatitis, cirrhosis of the liver, and cholecystitis.
Epstein-Barr Virus (EBV)
EBV is a ubiquitous human herpesvirus, causally associated with infectious mononucleosis (IM) and considered to be etiologicallyassociated with a still increasing number of disease syndromes, including African Burkitt’s lymphoma, nasopharyngeal carcinoma (NPC), some forms of Hodgkin’s disease, and some additional benign or malignant proliferative syndromes of epithelial or lymphatic origin. Following primary infection, the virus persists in the latent form, tightly controlled by the host’s immune sytem. This balance is reflected by the continuous presence of circulating lgG antibodies to proteins of the VCA complex and a latent antigen complex, namely Epstein-Barr Nuclear antigens (EBNA).
Prostate-specific antigen (PSA)
PSA is a tumor marker for prostate cancer. PSA is a protein made by cells of the prostate gland, which is found only in men.
The level of PSA in the blood can be elevated in prostate cancer, but PSA levels can be affected by other things, too. Men with benign prostatic hyperplasia (BPH), a non-cancerous growth of the prostate, often have higher levels. The PSA level also tends to be higher in older men and those with infected or inflamed prostates. It can also be elevated for a day or 2 after ejaculation.
CA 15-3 levels are most useful in following the course of treatment in women diagnosed with breast cancer, especially advanced breast cancer. CA 15-3 levels are rarely elevated in women with early stage breast cancer. Cancers of the ovary, lung, and prostate may also raise CA 15-3 levels. Elevated levels of CA 15-3 may be associated with non-cancerous conditions, such as benign breast or ovarian disease, endometriosis, pelvic inflammatory disease, and hepatitis. Pregnancy and lactation can also cause CA 15-3 levels to rise.
CA 125 is produced by a variety of cells, but particularly by ovarian cancer cells. Studies have shown that many women with ovarian cancer have elevated CA 125 levels. CA 125 is recommended as a screening test for ovarian cancer when there is a history of hereditary cancer syndrome (a pattern of clusters of ovarian cancer within two or more generations).
Not all women with elevated CA 125 levels have ovarian cancer. CA 125 levels may also be elevated by cancer of the uterus, cervix, pancreas, liver, colon, breast, lung, and digestive tract. Non-cancerous conditions that can cause elevated CA 125 levels include endometriosis, pelvic inflammatory disease, peritonitis, pancreatitis, liver disease, and any condition that inflames the pleura (the tissue that surrounds the lungs and lines the chest cavity). Menstruation and pregnancy can also cause an increase in CA 125.
Disclaimer: Not all blood tests that appear to be abnormal put your health at risk. Only a trained doctor can properly interpret your blood tests. A blood test is only one of many tools a doctor uses to evaluate your health. If you have any questions or concerns about any of your blood tests you should contact your doctor.
This is only general information. A doctor should be contacted if you need any medical advice or if medical decisions need to be made.