Table of ContentsView AllTable of ContentsPurposeCancers Monitored With CEAThe TestInterpreting Results
Table of ContentsView All
View All
Table of Contents
Purpose
Cancers Monitored With CEA
The Test
Interpreting Results
Carcinoembryonic antigen(CEA) is a tumor marker found in the blood or in other bodily fluids that can be used to monitor treatment for certain cancers.
This article explains what the CEA test is, when it can be helpful in cancer treatment, and how to interpret its results.
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Purpose of the Test
CEA levels may be high in connection with a number of conditions. As a result, this test cannot establish a cancer diagnosis on its own and is not used as a general screening tool for cancer.
Instead, healthcare providers will look at CEA levels over time, along with imaging studies and other tests, to help plan and monitor cancer treatment. When levels of CEA decrease, it may indicate that a cancer is responding to treatment. When CEA levels increase, it may suggest a recurrence, progression, or spread (metastasis) of the cancer.
Meaning of Carcinoembryonic Antigen (CEA)
The name “carcinoembryonic” refers to common sources of the CEA protein, with “carcino-” representing the tumor and “embryonic” referring to the fact that high levels of CEA are present in a fetus during development.
Uses/Indications
Your healthcare provider may test CEA levels in a number of circumstances, including the following.
CEA is most commonly used with digestive tract cancers.It may also be used as a tumor marker test to monitor a number of different cancer types, including:
Limitations
One significant limitation of the CEA test is that it is not increased in all cancers, and is not as likely to be present in a cancer’s early stages. This is one reason why it’s not an effective screening test. For example, It is present in roughly 70 percent to 80 percent of advanced colon cancers, but only in around 25 percent of early-stage colon tumors.
False Positives
There are also many benign (noncancerous) and inflammatory conditions that can increase CEA, leading tofalse positiveresults.
Benign conditions associated with an increase in CEA levels include:
Another limitation is that CEA levels may not reflect what is happening with a tumor at the time of the test. For example, CEA levels may be very high during and after chemotherapy.
Ascancer cellsdie, CEA is released into the bloodstream. Levels can remain elevated for a few weeks after treatment, even if a tumor is responding well.
Similar Tests
There are a number of othertumor markersthat can be used to monitor cancer treatment, though the particular markers that are tested vary with the type of cancer being followed. For example:
Complementary Tests
CEA levels are not used alone to monitor cancer, but rather are used along with symptoms, physical findings, other tumor markers or biomarkers, and imaging studies (such as a CT scan) to evaluate cancer and plan treatment.
Risks/Contraindications
There is very little risk in doing a CEA test, since it is a simple blood test.Uncommon side effects include bleeding, bruising (hematomas), lightheadedness, or fainting during the blood draw, as well as, rarely, infection.
The CEA test may be done in the hospital or in a clinic. The test is often run on a blood sample, but may also be run on fluid obtained from the central nervous system (via a lumbar puncture orspinal tap), from the pleural cavity (viathoracentesis), or from the peritoneal cavity (viaparacentesis). The description below refers to having the test done in the most common way: through a blood test.
Before the Test
There are no diet or activity restrictions prior to having the CEA test. You will usually be required to have your insurance card.
During the Test
A lab technician will cleanse the area over the vein to be used (usually an arm vein) with antiseptic, then apply a tourniquet. You may feel a sharp sting as the needle is introduced into the vein, then some slight pressure.
After the sample is obtained, the needle is removed and a bandage is placed over the puncture site. Some people may feel lightheaded or faint when having their blood drawn. Let the technician know if you have had any problems in the past or if you feel “funny” during the blood draw.
After the Test
The sample will be sent to the laboratory for analysis. Possible side effects after the test are very uncommon, but may include:
A single CEA test may give doctors some idea about what is happening in your body. The test should be repeated if it is abnormal to verify the result.
CEA levels are most helpful when repeated over time to observe how they change. As a result, “serial testing” gives more information than a single test.
Reference Range
The levels of CEA that are considered “normal” may vary somewhat between different labs. In general, a normal CEA in an adult is as follows:
High CEA
There are a number of both benign and cancerous conditions that may cause an elevated CEA level.
Causes of a High CEA LevelA CEA over 2.5 (or 5.0 in smokers) can mean either cancer or benign inflammatory conditions (or both).A CEA over 10.0 ng/ml often means cancer.A CEA over 20.0 ng/ml often means cancer that hasmetastasized.Very high levels (sometimes well over 100 ng/ml) are frequently seen with metastases to the pleural cavity, peritoneal cavity, and central nervous system.
Causes of a High CEA Level
A CEA over 2.5 (or 5.0 in smokers) can mean either cancer or benign inflammatory conditions (or both).A CEA over 10.0 ng/ml often means cancer.A CEA over 20.0 ng/ml often means cancer that hasmetastasized.Very high levels (sometimes well over 100 ng/ml) are frequently seen with metastases to the pleural cavity, peritoneal cavity, and central nervous system.
Certainly, there are many exceptions to this general rule. For example, a CEA over 20.0 may be due to an early-stage cancer plus a benign condition, such as hypothyroidism in a person who smokes.
As noted, CEA is often most useful when repeated over time. The amount of time between tests, however, can vary based on many factors.
For example, when surgery is done with curative intent for people with stage II or stage III colon cancer, a CEA is usually recommended every three months for at least three years after surgery. With treatment of metastatic colon cancer, in contrast, the test is often done every one month to three months.
Summary
A CEA test may be useful in monitoring cancer treatment, but it’s important to note that it should not be used alone as it is a lot less reliable than monitoring through imaging exams, for example. It is most helpful when it is monitored longitudinally over time rather than as a single value at a single time point.
Since CEA levels can take some time to decrease duringcolon cancer treatment, a healthcare provider will consider the whole picture rather than make treatment decisions based on CEA levels alone.
5 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Tong G, Xu W, Zhang G, et al.The Role of Tissue and Serum Carcinoembryonic Antigen in Stages I to III of Colorectal Cancer-A Retrospective Cohort Study.Cancer Med. 2018;7(11):5327-5338. doi:10.1002/cam4.1814Colloca GA, Venturino A, Guarneri D.Carcinoembryonic Antigen Reduction after Medical Treatment in Patients with Metastatic Colorectal Cancer: A Systematic Review and Meta-analysis.Int J Colorectal Dis. 2019;34(4):657-666. doi:10.1007/s00384-018-03230-wAcharya A, Markar SR, Matar M, Ni M, Hanna GB.Use of Tumor Markers in Gastrointestinal Cancers: Surgeon Perceptions and Cost-Benefit Trade-Off Analysis.Ann Surg Oncol. 2017;24(5):1165-1173. doi:10.1245/s10434-016-5717-yU.S. National Library of Medicine. MedlinePlus.Tumor marker tests.Saito G, Sadahiro S, Kamata H, et al.Monitoring of Serum Carcinoembryonic Antigen Levels after Curative Resection of Colon Cancer: Cutoff Values Determined According to Preoperative Levels Enhance the Diagnostic Accuracy for Recurrence.Oncology. 2017;92(5):276-282. doi:10.1159/000456075Additional ReadingBast, R., Croce, C., Hait, W. et al.Holland-Frei Cancer Medicine. Wiley Blackwell, 2017.
5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Tong G, Xu W, Zhang G, et al.The Role of Tissue and Serum Carcinoembryonic Antigen in Stages I to III of Colorectal Cancer-A Retrospective Cohort Study.Cancer Med. 2018;7(11):5327-5338. doi:10.1002/cam4.1814Colloca GA, Venturino A, Guarneri D.Carcinoembryonic Antigen Reduction after Medical Treatment in Patients with Metastatic Colorectal Cancer: A Systematic Review and Meta-analysis.Int J Colorectal Dis. 2019;34(4):657-666. doi:10.1007/s00384-018-03230-wAcharya A, Markar SR, Matar M, Ni M, Hanna GB.Use of Tumor Markers in Gastrointestinal Cancers: Surgeon Perceptions and Cost-Benefit Trade-Off Analysis.Ann Surg Oncol. 2017;24(5):1165-1173. doi:10.1245/s10434-016-5717-yU.S. National Library of Medicine. MedlinePlus.Tumor marker tests.Saito G, Sadahiro S, Kamata H, et al.Monitoring of Serum Carcinoembryonic Antigen Levels after Curative Resection of Colon Cancer: Cutoff Values Determined According to Preoperative Levels Enhance the Diagnostic Accuracy for Recurrence.Oncology. 2017;92(5):276-282. doi:10.1159/000456075Additional ReadingBast, R., Croce, C., Hait, W. et al.Holland-Frei Cancer Medicine. Wiley Blackwell, 2017.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Tong G, Xu W, Zhang G, et al.The Role of Tissue and Serum Carcinoembryonic Antigen in Stages I to III of Colorectal Cancer-A Retrospective Cohort Study.Cancer Med. 2018;7(11):5327-5338. doi:10.1002/cam4.1814Colloca GA, Venturino A, Guarneri D.Carcinoembryonic Antigen Reduction after Medical Treatment in Patients with Metastatic Colorectal Cancer: A Systematic Review and Meta-analysis.Int J Colorectal Dis. 2019;34(4):657-666. doi:10.1007/s00384-018-03230-wAcharya A, Markar SR, Matar M, Ni M, Hanna GB.Use of Tumor Markers in Gastrointestinal Cancers: Surgeon Perceptions and Cost-Benefit Trade-Off Analysis.Ann Surg Oncol. 2017;24(5):1165-1173. doi:10.1245/s10434-016-5717-yU.S. National Library of Medicine. MedlinePlus.Tumor marker tests.Saito G, Sadahiro S, Kamata H, et al.Monitoring of Serum Carcinoembryonic Antigen Levels after Curative Resection of Colon Cancer: Cutoff Values Determined According to Preoperative Levels Enhance the Diagnostic Accuracy for Recurrence.Oncology. 2017;92(5):276-282. doi:10.1159/000456075
Tong G, Xu W, Zhang G, et al.The Role of Tissue and Serum Carcinoembryonic Antigen in Stages I to III of Colorectal Cancer-A Retrospective Cohort Study.Cancer Med. 2018;7(11):5327-5338. doi:10.1002/cam4.1814
Colloca GA, Venturino A, Guarneri D.Carcinoembryonic Antigen Reduction after Medical Treatment in Patients with Metastatic Colorectal Cancer: A Systematic Review and Meta-analysis.Int J Colorectal Dis. 2019;34(4):657-666. doi:10.1007/s00384-018-03230-w
Acharya A, Markar SR, Matar M, Ni M, Hanna GB.Use of Tumor Markers in Gastrointestinal Cancers: Surgeon Perceptions and Cost-Benefit Trade-Off Analysis.Ann Surg Oncol. 2017;24(5):1165-1173. doi:10.1245/s10434-016-5717-y
U.S. National Library of Medicine. MedlinePlus.Tumor marker tests.
Saito G, Sadahiro S, Kamata H, et al.Monitoring of Serum Carcinoembryonic Antigen Levels after Curative Resection of Colon Cancer: Cutoff Values Determined According to Preoperative Levels Enhance the Diagnostic Accuracy for Recurrence.Oncology. 2017;92(5):276-282. doi:10.1159/000456075
Bast, R., Croce, C., Hait, W. et al.Holland-Frei Cancer Medicine. Wiley Blackwell, 2017.
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