CEA is most useful to monitor treatment of cancer patients. It is used for patients who have had surgery, to measure response to therapy and to monitor whether the disease has recurred. A blood test for CEA in this circumstance is used as a tumour marker, i.e. an indicator of whether the cancer is present or not. CEA is used as a marker for bowel cancer in particular, but may be measured where other forms of cancer are present. It has been found helpful in monitoring some patients with cancer of the rectum, lung, breast, liver, pancreas, stomach, and ovary. Not all cancers produce CEA, and a level within the given reference range does not guarantee that cancer (even the kinds known to produce CEA) is not present, therefore the CEA test is not used for screening the general population.
A CEA test may be requested when the patient's symptoms suggest the possibility of cancer. CEA is most useful however, when measured in patients with cancers known to produce the protein before and during or after treatment. It is also used to follow up patients after treatment.
The concentration of CEA in the blood does not accurately reflect tumour size, however on initial testing, patients with smaller and early-stage tumours are likely to have low, if not normal, CEA concentrations, while patients with more advanced tumours, or tumours that have spread throughout the body, are likely to have initially high CEA concentrations. When CEA decreases to "normal" concentrations after therapy, it means that the CEA-producing tumour has been removed. A steadily rising CEA result may be the first sign that the cancer has returned.
CEA is a protein that is found in developing tissues of babies. By the time a baby is born, detectable levels in the blood disappear. Increased CEA concentrations can indicate some non-cancer-related conditions, such as liver disease, and inflammatory bowel disease. Also, smokers tend to have higher concentrations in the blood than non-smokers.
This article was last reviewed on 16 January 2014. | This article was last modified on 7 April 2014.
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