What is a TP53 genetic test?
A TP53 genetic test looks for a change, known as a mutation, in a gene called TP53 (tumor protein 53). Genes are the basic units of heredity passed down from your mother and father.
TP53 is a gene that helps stop the growth of tumors. It’s known as a tumor suppressor. A tumor suppressor gene works like the brakes on a car. It puts the “brakes” on cells, so they don’t divide too quickly. If you have a TP53 mutation, the gene may not be able to control the growth of your cells. Uncontrolled cell growth can lead to cancer.
A TP53 mutation can be inherited from your parents, or acquired later in life from the environment or from a mistake that happens in your body during cell division.
Acquired (also known as somatic) TP53 mutations are much more common. These mutations have been found in about half of all cases of cancer, and in many different types of cancer.
Other names: TP53 mutation analysis, TP53 full gene analysis, TP53 somatic mutation
What is it used for?
The test is used to look for a TP53 mutation. It is not a routine test. It is usually given to people based on family history, symptoms, or previous diagnosis of cancer.
Why do I need a TP53 genetic test?
You may need a TP53 test if:
- You’ve been diagnosed with a bone or soft tissue cancer before the age of 45
- You’ve been diagnosed with, pre-menopausal breast cancer, a brain tumor, leukemia, or lung cancer before the age of 46
- You’ve had one or more tumors before the age of 46
- One or more of your family members have been diagnosed with Li-Fraumeni syndrome and/or have had cancer before the age of 45
These are signs you may have an inherited mutation of the TP53 gene.
If you’ve been diagnosed with cancer and don’t have a family history of the disease, your health care provider may order this test to see if a TP53 mutation may be causing your cancer. Knowing whether you have the mutation can help your provider plan treatment and predict the likely outcome of your disease.
What happens during a TP53 genetic test?
A TP53 test is usually done on blood or bone marrow.
If you are getting a blood test, a health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
If you are getting a bone marrow test, your procedure may include the following steps:
- You’ll lie down on your side or your stomach, depending on which bone will be used for testing. Most bone marrow tests are taken from the hip bone.
- Your body will be covered with cloth, so that only the area around the testing site is showing.
- The site will be cleaned with an antiseptic.
- You will get an injection of a numbing solution. It may sting.
- Once the area is numb, the health care provider will take the sample. You will need to lie very still during the tests.
- The health care provider will use a special tool that twists into the bone to take out a sample of bone marrow tissue. You may feel some pressure on the site while the sample is being taken.
- After the test, the health care provider will cover the site with a bandage.
- Plan to have someone drive you home, since you may be given a sedative before the tests, which may make you drowsy.
Will I need to do anything to prepare for the test?
You usually don’t need any special preparations for a blood or bone marrow test.
Are there any risks to the test?
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
After a bone marrow test, you may feel stiff or sore at the injection site. This usually goes away in a few days. Your health care provider may recommend or prescribe a pain reliever to help.
What do the results mean?
If you’ve been diagnosed with Li-Fraumeni syndrome, it does not mean you have cancer, but your risk is higher than most people. But if you have the mutation, you can take steps to reduce your risk, such as:
- More frequent cancer screenings. Cancer is more treatable when found in the early stages.
- Making lifestyle changes, such as getting more exercise and eating a healthier diet
- Chemoprevention, the taking of certain medicines, vitamins, or other substances to reduce the risk or delay the development of cancer.
- Removing “at-risk” tissue
These steps will vary depending on your health history and family background.
If you have cancer and your results indicate an acquired TP53 mutation (a mutation was found, but you have no family history of cancer or Li-Fraumeni syndrome), your provider can use the information to help predict how your disease will develop and guide your treatment.
Is there anything else I need to know about a TP53 test?
If you’ve been diagnosed with or suspect you have Li-Fraumeni syndrome, it may help to speak to a genetic counselor. A genetic counselor is a specially trained professional in genetics and genetic testing. If you haven’t yet been tested, the counselor can help you understand the risks and benefits of testing. If you have been tested, the counselor can help you understand the results and direct you to support services and other resources.