The carcinoembryonic antigen (CEA) test measures the amount of this
protein that may appear in the blood of some people
who have certain kinds of cancers, especially large intestine (colon and rectal) cancer. It may also be present in people with cancer of the
pancreas, breast, ovary, or lung.
CEA is normally produced during the development of a
fetus. The production of CEA stops before birth, and
it usually is not present in the blood of healthy adults.
Why It Is Done
The carcinoembryonic antigen (CEA) test is used to:
Find how widespread cancer is for some types of
the disease, especially colon cancer.
Check the success of
treatment for colon cancer.
CEA levels may be measured both before and
after surgery to evaluate both the success of the surgery and the person's
chances of recovery.
CEA levels may be measured during treatment
with medicines to destroy cancer cells (chemotherapy).
This provides information about how well the treatment is working.
Check to see if cancer has returned after
treatment.
How To Prepare
You do not need to do anything before you have this test.
Talk to your health professional about any concerns you have
regarding the need for the test, its risks, how it will be done, or what the
results will indicate. To help you understand the importance of this test, fill
out the
medical test information form(What is a PDF document?)
.
How It Is Done
The health professional taking a sample of your blood will:
Wrap an elastic band around your upper arm to
stop the flow of blood. This makes the veins below the band larger so it is
easier to put a needle into the vein.
Clean the needle site with
alcohol.
Put the needle into the vein. More than one needle stick
may be needed.
Attach a tube to the needle to fill it with
blood.
Remove the band from your arm when enough blood is
collected.
Put a gauze pad or cotton ball over the needle site as
the needle is removed.
Put pressure to the site and thenput on a
bandage.
How It Feels
The blood sample is taken from a vein in your arm. An elastic band
is wrapped around your upper arm. It may feel tight. You may feel nothing at
all from the needle, or you may feel a quick sting or pinch.
Risks
There is very little chance of a problem from having blood drawn
from a vein.
You may get a small bruise at the site. You can
lower the chance of bruising by keeping pressure on the site for several
minutes.
In rare cases, the vein may become swollen after the
blood sample is taken. This problem is called phlebitis. A warm compress can be
used several times a day to treat this.
Ongoing bleeding can be a
problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and
other blood-thinning medicines can make bleeding more likely. If you have
bleeding or clotting problems, or if you take blood-thinning medicine, tell
your doctor before your blood sample is taken.
Results
The carcinoembryonic antigen (CEA) test measures the amount of this
protein that may appear in the blood of some people
who have certain kinds of cancers, especially large intestine (colon and rectal) cancer. It may also be present in people with cancer of the
pancreas, breast, ovary, or lung.
Many conditions can change your CEA levels. Your doctor will
discuss any significant abnormal results with you in relation to your symptoms
and medical history.
Most cancers do not produce this protein, so your CEA may be normal
even though you have cancer.
High values
Cancer of the colon, lung, pancreas, breast,
or ovary may be present.
Cancer may not be responding to
treatment.
Cancer may have returned after treatment. A steadily
rising CEA may be the first sign that cancer has come back after treatment.
Also, people with advanced cancer or cancer that has spread to other parts of
the body (metastatic cancer) may have high CEA levels if their original cancer
produced this protein before treatment.
People with small cancers or early-stage
disease usually have low, or even normal, CEA levels.
What Affects the Test
Heavy smoking affects the test results.
What To Think About
The CEA blood test is not reliable for
diagnosing cancer or as a screening test for early detection of
cancer.
CEA testing is a reliable test for recurrent colon cancer
if the original cancer produced this protein before treatment.
Most
types of cancer do not produce a high CEA. Having a normal CEA level does not
mean that you do not have cancer.
CEA levels usually return to
near-normal levels within 6 weeks of starting treatment if cancer treatment is
successful.
Measuring the amount of CEA in other body fluids, such as
abdominal fluid (peritoneal fluid) or the fluid around the brain and spinal
cord (cerebrospinal fluid, or CSF), can determine whether
cancer has spread to that part of the body.
Other diseases, such as
COPD, cirrhosis, and
Crohn's disease, may also raise CEA blood levels.
CEA levels are usually higher in smokers than in
people who do not smoke.
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