TP53 Genetic Test

What is a TP53 genetic test?

A TP53 genetic test uses a sample of your blood, bone marrow, or tissue from a tumor 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.

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 help prevent or slow the growth of cells that may become tumors. The proteins work by:

• Preventing cells from dividing too quickly to make new cells.
• Repairing damaged DNA in cells.
• Starting the normal process of cell death in cells that can't be repaired.

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 are not passed down from your parents. They develop at some time after you're born. These kinds of changes are extremely common, accounting for more than half of all adult cancers. Where you develop these gene changes, and how likely you are to develop them, depends on a variety of factors. These include:

• Errors in DNA repair or when cells divide to make new cells. These errors can happen at any time. However, they become more common with age. They are also more common in some cells than others. For example, TP53 gene changes are especially common in breast tissue cells.
• Being exposed to certain carcinogens (substances that increase your likelihood of getting cancer). For example, exposure to cigarette smoke or diesel exhaust can lead to TP53 gene changes in your lungs. Similarly, exposure to UV radiation from the sun and some artificial sources like tanning beds can lead to these changes in your skin.
• Having certain chronic viral infections, such as HPV. These viruses can damage your DNA and lead to TP53 gene changes in your cervix.

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 from parent to child. 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, including cancer of the breast, bone, and 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. If you do have a TP53 gene change, your health care provider may prioritize some treatments over others that wouldn't work on cancers without this gene change.
• 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 genetic test if you have:

• Been diagnosed with cancer.
• A personal and/or family health history you may have inherited Li-Fraumeni Syndrome.

If you have been diagnosed with cancer, this test can check whether an acquired change in your TP53 gene is causing it. This information can help your provider select the right treatment and predict how your cancer may behave over time.

If you have a personal and/or family health history that suggests Li-Fraumeni Syndrome, your provider may not only test you, but also some of your family members. Talk with your provider or a genetic counselor about testing if you or your family members have had cancers that are closely linked to this 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 genetic 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. There are many ways to do a biopsy. The type of biopsy you have depends on the type of cancer you have and where the tumor is located. In general, a biopsy may be done using:

• A hollow needle inserted through your skin. Imaging tests, such as ultrasound, may be used to guide the needle.
  • A fine needle aspiration biopsy uses a very thin needle to remove a sample of cells and/or fluid.
  • A core needle biopsy uses a larger needle to remove a sample.
• Surgery. Surgery may be done to remove a sample of tissue (an incisional biopsy). In certain cases, the entire tumor will be removed (an excisional biopsy).
• Endoscopy. This procedure uses a scope to look inside your body. Special tools may be used with a scope to remove a sample of tumor tissue. Different types of endoscopy may be used depending on where the tumor is located.

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.

Learn more about laboratory tests, reference ranges, and understanding results.

Is there anything else I need to know about a TP53 genetic 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.