A TP53 genetic test usually uses a sample of your blood to look for changes in the tumor protein 53 gene, or TP53 for short. Changes in your genes are also called gene variants or mutations. Changes in the TP53 gene are linked to many different types of cancer.
Genes are parts of DNA in your cells that you inherit from your parents. You inherit two copies of each gene, one from each parent. Genes carry information that controls what you look like and how your body works.
TP53 is a type of gene called a “tumor suppressor.” Tumor suppressor genes provide instructions for making proteins that control how fast your cells grow and divide to make new cells. TP53 proteins also help stop the growth of abnormal cells.
If you have certain changes in a TP53 gene, the gene or the protein it makes may not work well or may stop working completely. As a result, your cells may grow out of control, which can lead to tumors and cancer. Changes in your TP53 gene can be acquired or inherited.
Acquired changes in your genes develop at some time after you’re born. Most changes in TP53 genes are acquired changes. More than half of all adult cancers involve a change in this gene.
Acquired changes in your TP53 gene:
- Can happen if your cells make a mistake when they divide to make new cells
- Can happen if you’re exposed to substances that cause cancer
- Show up only in certain types of cells
- Usually aren’t in sperm or egg cells, so you can’t pass them down to children
Inherited changes in your genes are changes that you’re born with. They show up in all the cells in your body, including your egg or sperm cells. That means they can be passed down to your children. Inherited changes in the TP53 gene cause a rare genetic condition called Li-Fraumeni syndrome (LFS). It increases your risk of developing certain types of cancer. Cancers that are linked to Li-Fraumeni syndrome commonly happen in the breast, bone, or muscles.
Other names: TP53 mutation analysis, TP53 full gene analysis, TP53 somatic mutation
What is it used for?
A TP53 genetic test is used to look for changes in your TP53 genes. It’s not a routine test. It is often used to:
- Help choose treatment for people who have cancer
- Check for inherited changes in the TP53 gene in people who have a personal or family history of cancers that may be linked to Li-Fraumeni syndrome
Why do I need a TP53 genetic test?
You may need a TP53 test if you:
- Have been diagnosed with cancer. The test can check whether an acquired change in your TP53 gene is causing your cancer. This information can help your provider select the right treatment and predict how your cancer may behave over time.
- Have a personal and/or family health history that suggests you may have inherited Li-Fraumeni syndrome. Providers may use different sets of guidelines to decide who needs to be tested for Li-Fraumeni syndrome. Talk with your provider or a genetic counselor about testing if you or your family members have had cancers that are closely linked to Li-Fraumeni syndrome. These cancers include:
- Osteosarcoma, a form of bone cancer
- Soft tissue sarcoma, cancer of the muscle and connective tissues
- Breast cancer
- Brain tumors
- Acute (sudden) leukemia
- Adrenal cortical carcinoma, a type of adrenal gland cancer
What happens during a TP53 genetic test?
A TP53 test is often done on a sample of blood. Tissue from a tumor or bone marrow may sometimes be used instead. Bone marrow is a spongy tissue found inside most bones.
For 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.
For tumor tissue testing, tissue is removed during a procedure called a biopsy. A biopsy may be done in different ways depending on where the tumor is located. A provider may use a hollow needle or surgery to take a tissue sample from a tumor.
For a bone marrow test, a provider usually takes a sample from the back of your hip bone. You will be given an injection (shot) of medicine to numb the area. You may also be given medicine to help you relax or sleep.
A bone marrow test has two parts that are usually done one after the other:
- For a bone marrow aspiration, the provider pushes a hollow thin needle into the bone. A sample of bone marrow fluid is removed using a syringe attached to the needle.
- For a bone marrow biopsy, the provider inserts a larger hollow needle into the bone and twists the needle to take out a small piece of bone marrow tissue.
The procedure takes only a few minutes. You may feel pressure or a brief, sharp pain when the samples are being taken. Afterwards, the area will be bandaged. You’ll stay lying down for about 15 minutes to make sure the bleeding stops. You may need to stay longer if you had medicine to relax or sleep.
Will I need to do anything to prepare for the test?
A blood test usually doesn’t require any preparation. If you’re having a tissue biopsy or a bone marrow test, ask your provider how you should prepare. If you will be given medicine to relax or sleep, plan to have someone take you home after the test in case you are drowsy.
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 tissue biopsy or a bone marrow test, you may have some soreness where the sample was taken. This usually goes away in a few days. If you need pain relief, talk with your provider.
What do the results mean?
If you have cancer and your results show you have an acquired change in your TP53 gene, ask your provider how this information affects your treatment plan and future health.
If your test results show you have an inherited change in one copy of your TP53 gene, you have Li-Fraumeni syndrome. This doesn’t mean you have cancer. But your risk of getting cancer is higher than most people. Talk with your provider about the steps you can take to reduce your risk of cancer. Your provider may discuss:
- Having frequent cancer screening tests to help find cancer early when it may be easier to treat
- Having a yearly physical exam
- Making lifestyle changes, such as getting more exercise, eating a healthier diet, and quitting smoking
- Chemoprevention, which is taking certain medicines or other substances to reduce the risk of developing cancer or to keep it from coming back
- Mastectomy to help prevent breast cancer
The right steps for you will depend on your age, health history, and family health history.
Is there anything else I need to know about a TP53 test?
If you think you may have Li-Fraumeni syndrome, it may help to talk with a genetic counselor before getting tested. The counselor can help you understand the risks and benefits of testing for you and your family. This can help you make informed decisions.
If you are diagnosed with Li-Fraumeni syndrome, a counselor can explain your risk for cancer and discuss whether family members should be tested. A genetic counselor can also help you make plans to manage your risk over time.
Courtesy of MedlinePlus from the National Library of Medicine.