HealthCentral writers PJ and Phyllis were lifelines for me when my wife was going through treatment for stage I invasive breast cancer. She is doing great as a seven-year survivor. I remember learning that CEA levels can often fluctuate and be unreliable. How concerning is her 13 CEA reading?
One high carcinoembryonic antigen (CEA) reading is not a cause for concern, although it might prompt a doctor to do more testing depending on the patient’s other symptoms.
The CEA test measures a specific protein in the blood called carcinoembryonic antigen. The amount of this protein is measured in nanograms per milliliter (ng/mL). Normal levels vary depending on a patient’s age and some other factors, but they generally are less than 5 ng/mL.
The test is one of many tumor markers that a doctor may use to monitor cancer. CEA levels are most frequently used in colorectal cancer, but may be used with several other cancers too, including breast cancer.
Guidelines from the American Society of Clinical Oncology (ASCO) state that tumor markers like the CEA should never be used alone to assess a patient’s disease level.
Why are tumor markers an unreliable indicator of cancer progression? Our bodies have normal fluctuations. For example, if your doctor has been monitoring your glucose or cholesterol levels, you have probably noticed that they go up and down. One study in 2014 at Memorial Sloan Kettering Cancer Center found that 49 percent of the CEA tests done with colorectal cancer patients were false positives — they were higher than 5 ng/mL, but the patient did not have a cancer recurrence.
Another reason tumor markers can vary is that laboratories may use different methods, so a value taken one year may be different from a previous year if the methodology was not the same.
Sometimes the problem is an error in taking or storing the sample or reading the results in the lab.
So why do doctors bother doing tumor marker tests? When they rise or measure consistently high over a period of time, they may indicate a reason for more thorough investigation. A blood test is less invasive and expensive than imaging tests and biopsies, so it can be one useful way to monitor a patient’s progress when used with clinical observation, imaging tests, and biopsies. Tumor markers are frequently used in patients with metastatic disease to gauge how well treatments are working.
Allen wrote in later to report that further testing found no cancer, and all is well.
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You should know: The answer above provides general health information that is not intended to replace medical advice or treatment recommendations from a qualified healthcare professional.
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