- CEA is most useful to monitor treatment of cancer patients. It is used with patients who have had surgery to measure response to therapy and to monitor whether the disease is recurring. A blood test for CEA is often used as a tumor marker. Physicians can use CEA results to determine the stage and extent of disease, and the outlook in patients with cancer, especially gastrointestinal (GI) and, in particular, colorectal cancer. CEA is also used as a marker for other forms of cancer. It has been found helpful in monitoring patients with cancer of the rectum, lung, breast, liver, pancreas, stomach, and ovary. Not all cancers produce CEA, therefore the CEA test is not used for screening the general population.
- A CEA test is ordered when the patient’s symptoms suggest the possibility of cancer. The CEA level is also tested before treatment in cancer patients, especially patients with GI cancers. CEA levels are monitored during therapy. It is also used to follow up patients after therapy.
- On initial testing, patients with smaller and early-stage tumors are likely to have low, if not normal, CEA levels, while patients with more advanced tumors, or tumors that have spread throughout the body, are likely to have initially high CEA levels. When CEA levels decrease to “normal” levels after therapy, it means that the CEA-producing tumor has been removed. A steadily rising CEA level is occasionally the first sign of tumor recurrence. When cancer spreads to other organs, CEA levels rise and may be present in other types of bodily fluids besides blood. For example, if CEA is detected in cerebrospinal fluid, this indicates a central nervous system metastasis.
