CEA (Cancer-fetal antigen) – research, standards, interpretation

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Cancer-fetal antigen (CEA) is a glycoprotein with multiple tissue domains. Determining its level is important in monitoring the effectiveness of oncological treatment. CEA antigen testing is performed when liver, intestine or pancreatic cancer is suspected. The material needed for the test is serum.

What is CEA antigen?

The carcinoembryonic antigen in the gastrointestinal tract is located in the glycocalyx of epithelial cells, from which it is released into its lumen. The main application of the CEA antigen is the diagnosis of recurrent tumors of the anus and colon after surgical treatment.

The test is carried out both before and after the operation to remove the tumor cells. Thanks to it, it is possible to determine if the cancer has not come back or to estimate the likelihood of a patient returning to neoplastic changes. The concentration of CEA also increases slightly in inflammation of the liver and intestines.

The carcinoembryonic protein test is used as a screening test and can also be used to check the effectiveness of treatment in cancer patients. Usually, the CEA test does not cause any complications, only a small bruise may appear at the site of blood collection. Increased bleeding may occur after blood collection in patients who have blood clotting disorders or are taking acetylsalicylic acid or other anticoagulant medications.

CEA examination is also performed as a prophylactic examination of breast cancer.

See also: Colon cancer prevention

CEA – a neoplastic marker that detects cancer

Tumor markers are substances that relate to the cell surface of proteins, lipid or hormone enzymes, and cellular proteins. Their determination is performed in body fluids, primary tumor mass, cells derived from metastases or in urine.

It should be taken into account that a large number of tumor markers do not have full specificity for tumors with a specific location, therefore their analysis should not be treated as a basic study. The examination of markers should complement other diagnostic techniques, e.g. imaging tests.

Marker marking can be performed in virtually any laboratory. They play the most important role in the treatment of cancer. After tumor excision, the patient performs markers determination before each consultation with the oncologist. Their increase means that the neoplastic process is still going on and it could have metastasized. Conversely, when the level of markers remains constant or declines: the development of the disease has stopped.

Find out more: Cancer markers for men – diagnostic tests

When do we test the CEA antigen?

The main indications for a carcinoembryonic antigen test are listed below.

  1. Suspected cancer of the liver, pancreas, intestines, anus, stomach, breasts, bile ducts, but also thyroid and lungs. The CEA antigen works particularly well in the case of colorectal cancer. 
  2. Monitoring the treatment of neoplastic diseases, checking whether the applied treatment (e.g. chemotherapy) gives positive results. 
  3. Controlling for metastases. 

There are no contraindications for the CEA test.

Also read: Are you worried that you are at risk of cancer? Perform a study of tumor markers for women

CEA antigen test – the course of the study

  1. Material for CEA testing: serum. In some cases, fluid is also withdrawn from the peritoneal cavity, pleural cavity, or cerebrospinal fluid. Venous blood is collected in a special test tube, then placed in ice water and sent to the laboratory. Sometimes serum is separated from the blood and delivered to the laboratory frozen.
  2. Preparation for the CEA examination: it is not necessary to be on an empty stomach, but it is recommended not to eat before the examination.
  3. The course of the CEA study: one-time blood sampling from a vein in the arm.
  4. Waiting time for the CEA result: 1 Day.
  5. CEA standard: less than 5 µg / l.
  6. Comments: Cancer-fetal CEA antigen is physiologically present in the organisms of fetuses – its elevated level after birth indicates pathology. CEA is produced by cancer cells in various organs. It also increases in inflammation of the liver, small and large intestines, and also in people who smoke.

CEA – norms and values

The CEA concentration for smokers should be below 5 pg/ml. These figures for non-smokers are reduced to below 2,5 pg/ml. An increase in the concentration of carcinoembryonic antigen in the blood serum may suggest:

  1. neoplasm: up to 20 pg / ml may indicate non-neoplastic malignant changes, e.g. large intestine, anus, lungs.
  2. neoplastic changes: usually up to 10 pg / ml, e.g. in diseases of the digestive system, enteritis, hepatitis, liver cirrhosis, pancreatitis.

Blood levels of CEA antigen above 40 mg / ml may suggest one of the following cancers:

  1. anus,
  2. bronchitis,
  3. thyroid gland,
  4. pancreas,
  5. liver,
  6. breasts
  7. large intestine.

A moderate increase of 5-40 mg / ml may suggest:

  1. enteritis, e.g. Crohn’s disease,
  2. gastric and duodenal ulcers,
  3. inflammation of the pancreas,
  4. kidney failure
  5. COPD (chronic obstructive pulmonary disease),
  6. blocked bile ducts,
  7. ulcerative colitis,
  8. pregnancy,
  9. cirrhosis.

When the doctor selects an effective treatment, the concentration of CEA antigen returns to normal after about six weeks. Carrying out the test using a different material, such as cerebrospinal fluid, helps to rule out metastases elsewhere in the body.

CEA antigen – study of tumor stages

Blood CEA testing has poor diagnostic specificitytherefore, it should not be used as a screening test for the detection of malignant neoplasms, but only as an adjunct to other methods of diagnosis.

However, it is worth knowing that the CEA antigen is a great indicator in cancer therapy. In the event that the tumor is surgically removed, the patient is then sent to the oncologist for a follow-up visit. Markers are marked before each consultation and if the CEA antigen level is elevated, it is a sign that the cancer process is most likely still going on and that it may metastasize.

When the CEA level is falling or is at a constant level, it is a sign that the development of the disease has stopped. In the case of radical surgery, normalization of the CEA antigen level from the serum is expected within 4 months.

By testing the CEA antigen, it is possible to accurately determine the effectiveness of the therapy and determine whether the cancer has recurred or how likely it is for a similar cancer to appear. Higher-than-normal levels of CEA antigen before surgery may indicate a risk of recurrence of the disease or liver metastases.

When we are dealing with colorectal cancer, a high CEA result is a bad prognosis, but it is irrelevant in the case of rectal cancer. Interestingly, the high concentration of CEA after surgery does not always have to be related to the recurrence of the neoplastic disease, because the CEA antigen may also be at a higher level in the case of intestinal and liver inflammations.

CEA antigen – complications

Complications in the determination of CEA antigen levels are very rare and are similar to complications resulting from other venous blood collection. It happens that a hematoma may appear at the injection site. The vein may swell immediately after puncture, which is associated with inflammation of the veins, much less frequently. If this is the case, warm compresses should be applied for the next few days after the examination, thanks to which the unpleasant symptoms will be alleviated.

In the case of people suffering from a blood clotting disorder or people who take anticoagulants, including acetylsalicylic acid, there may be an increase in bleeding after blood collection. It should be remembered that in the event of any complaints or abnormalities, the patient should immediately inform the medical staff about what medications he is currently taking, whether he has problems with blood clotting, especially hemorrhagic diathesis, and whether he smokes.

CEA antigen – statistics

The increase in CEA antigen concentration, although it may not be associated with cancer, is seen in: 70 percent of colorectal cancers, over 65 percent of non-small cell lung cancer, 55 percent of pancreatic cancers, 50 percent of stomach cancers, 45 percent of lung cancers, 40 percent of cervical cancers uterus, 40 percent of breast cancers, and 25 percent of ovarian cancers.

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