What is Carcinoembryonic antigen (CEA)
Carcinoembryonic antigen (CEA) is a glycoprotein involved in cell adhesion which health experts use to monitor cancer treatment. CEA is produced during fetal development and is not seen in the blood of healthy adult individuals but is present in individuals with lung carcinoma, breast carcinoma, gastric carcinoma, pancreatic carcinoma, thyroid carcinoma and colorectal carcinoma.
Conducting the CEA blood test
The test requires a blood sample from the vein, body fluids or biopsy tissue. After collection of the blood sample, it is subject to centrifuge to obtain blood serum. The CEA test requires 0.6 ml of serum. The minimum required amount of the specimen is 0.5 ml. The instruments that the test requires is a immunoassay system such as Beckman Coulter UniCel DXI 800. The method immunoenzymatic assay the serum, the specifications of the serum is that it should have mild hemolysis and mild lipemia. Other specifications of the sample collected are, to put the serum in a refrigerator away from sunlight and normal temperatures. The usual turnaround time of the test is 3 days, where the analytic time is 1 day. For colon cancer, the CEA blood test is reliable if the patient has produced the protein before treatment.
CEA Blood Test
Why the Test is Performed
A CEA test should be ordered when your symptoms are cancerous. Patients who’ve been clinically diagnosed with particular types of cancer, a CEA level is additionally assessed both before and after therapy, to guage the achievements of treatment.
CEA is also used as a tumor marker to identify recurrences after surgery and for other forms of cancer.
Types of cancer CEA is evident.
Not all cancers produce CEA, though with the CEA blood test and identifying cancer it is difficult and can be useful while monitoring cancer treatment such as colorectal cancer. Cancers may not produce exceptionally high CEA levels, but they produce sufficient levels to ascertain if the cancer treatment is successful after 6 weeks.
List of CEA Genes
CEA belongs to immunoglobulin super family and consists of 29 genes which encode carcinoembryonic antigen-related cell adhesion proteins.
Some of the genes, that humans have are CEACAM1, CEACAM2, CEACAM3, CEACAM4, CEACAM5, CEACAM6, CEACAM7, CEACAM8, CEACAM16, CEACAM19, CEACAM18, CEACAM20, and CEACAM21.
Monitoring of CEA levels of such patients can be helpful in determining the progress of treatment.
When the CEA levels are high, it means the cancer is in an advanced stage. The CEA level results when low indicate that the cancer is small or in an initial stage. For patients who have undergone cancer surgery, low CEA values suggest than the CEA producing tumor is not existent, and for those who have high CEA values after the surgery, it implies that the cancer is back.
High CEA Levels
If you have a high level of CEA then it may be the result of any of the following:
- For normal adults who do not smoke the acceptable limit is less than 2.5 ng/ml, and for those who smoke it is less than 5 ng/ml.
- CEA levels that are high before cancer surgery will fall later. If the CEA levels are greater than 20 ng/ml, it means the cancer has already spread through the body.
- Most of the cancers increase CEA levels, colon and rectum cancers increase it considerably.
- Chemotherapy and radiation treatment also temporarily raise CEA levels.
- This test especially works well when we know that the patient produces this protein.
Apart from the cancer other diseases which increase the CEA levels are COPD, cirrhosis and chrons disease.
To determine which part of the body the cancer has spread, check the CEA levels in other body fluids such abdominal fluid for abdomen, fluids in the brain for checking cancer in the brain and spinal cord fluid for checking the cancer in the spinal cord.