Doctors use tests such as blood tests, mammograms, MRIs, and CT scans to help them screen for, diagnose, treat, and monitor cancer. If you've been diagnosed with cancer, you may have had one or more of these tests. You may have wondered why you had certain tests and not others, and what exactly the doctor was looking for.
What types of tests are there?
There are many different kinds of tests that can be used. Some tests are done on a sample of your blood, urine, or tissue. Others are done on your whole body (such as an X-ray or CT scan). Most of the time, more than one test is done to diagnose or monitor cancer. Many of the tests used are not cancer-specific, but some are.
Tumor markers
The cancer or the body's response to the cancer may make substances that can be measured. They may only be made for one or more types of cancer. Or they may be caused by noncancer (benign) problems. Some of the markers are used more in monitoring during and after treatment. In this case, your healthcare provider is looking for changes in the marker levels over time. Here are some common molecular markers:
|
Selected tumor markers
|
Cancers that can cause increased levels
|
|
Alpha-fetoprotein (AFP)
|
Liver and germ cell cancers of the ovary or testicle
|
|
CA 15-3
|
Breast cancer
|
|
CA 19-9
|
Pancreatic, some colon, and biliary tract cancers
|
|
CA 27-29
|
Breast cancer
|
|
CA 125
|
Ovarian cancer
|
|
Carcinoembryonic antigen (CEA)
|
Colorectal, pancreatic, lung, breast, and ovarian cancer
|
|
Human chorionic gonadotropin (HCG)
|
Choriocarcinoma or gestational trophoblastic disease (a rare type of uterine cancer involving placental tissue) and germ cell cancers of the ovary or testicle
|
|
Prostate-specific antigen (PSA)
|
Prostate cancer
|
Molecular tumor markers may be measured in blood, urine, or tissue tests. They're used along with other tests to diagnose and monitor treatment. The usefulness of tumor markers depends on the stage and specific subtype of cancer. There are many other tumor marker tests that might be used.
Imaging tests
Imaging tests are used to find cancer inside the body. They're used to find the stage of the cancer and can help focus treatment (such as radiation or surgery) to the part of the body with cancer. Here are some common imaging tests:
|
Imaging test
|
How it works
|
|
CT scan
|
A computer uses X-rays to make detailed horizontal (axial) images of the inside of the body.
|
|
PET scan
|
A radioactively-linked sugar is put into the bloodstream. Images are then taken to see where sugar collects in the body.
|
|
MRI
|
Radio waves in a strong magnetic field are used to make a computer-generated, detailed image of the inside of the body.
|
|
Radionuclide imaging
|
The person is given radioactively-linked substances as an injection into the blood or by mouth (orally). Images are then taken to see where the body is using these substances (for instance, bone, liver, or thyroid scans).
|
|
Ultrasounds
|
Sound waves are used to create pictures of the inside of the body.
|
|
X-rays
|
A radiograph is used to create a 2-dimensional image of the inside of the body.
|
These questions may be helpful when talking with your healthcare provider about tests:
-
What tests do you think I need?
-
What will the test tell us?
-
What's it like to have the test?
-
Are there any special preparations needed for the test?
-
Are there any risks from the test?
-
How long does it take to get the results?
-
How will the information you get from the test help?
-
What other tests might be needed?
No test is 100% perfect. Sometimes a cancer is missed when it's really there (false negative). Or it may look like a person has cancer when they don't (false positive). Researchers are working on better, more sensitive tests to help diagnose, treat, and monitor cancer.