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Understanding Genetics, Gene Mutations, and Cancer Risk

Genetics is the field of science that looks at how traits (such as eye color) are passed down from parents to their children through genes.

Genes are pieces of DNA (deoxyribonucleic acid) inside our cells that tell the cell how to make the proteins the body needs to function. DNA is the genetic “blueprint” in each cell. Genes affect inherited traits passed on from a parent to a child, such as hair color, eye color, and height. They can also affect whether a person is likely to develop certain diseases, such as cancer.

Mutations are changes or gene rearrangements in the DNA that may lead to cancer.

Changes in genes, called mutations, play an important role in the development of cancer. Mutations can cause a cell to make (or not make) proteins that affect how the cell grows and divides into new cells. Certain mutations can cause cells to grow out of control, which can lead to cancer. About 5% to 10% of all cancers are thought to be strongly related to an inherited gene mutation.

Most cancers start because of acquired gene mutations that happen during a person’s lifetime. Sometimes these gene changes have an outside cause, such as exposure to sunlight or tobacco. But gene mutations can also be random events that sometimes happen inside a cell, without a clear cause.

Acquired mutations only affect the cells that grow from the mutated cell. They do not affect all the cells in the person’s body. This means all the cancer cells will have the mutations, but normal cells in the body will not. Because of this, the mutations are not passed on to a person’s children. This is very different from inherited mutations, which are in every cell in the body – even the cells without cancer.  

What is Genetic Testing?

Genetic testing is the use of medical tests to look for certain mutations in a person’s genes. Genetic testing can be used to look for gene changes linked to cancer.

RET

NTRK

EGFR

BRAF

ALK

HER2

MET

EGFR

HER2

NTRK

BRAF

RET

BRAF

NTRK

Why should my tumor be tested?

Some cancer treatments are called “targeted therapies” because they are designed to target specific tumor characteristics. It is important to know if you have a tumor with one of these characteristics so you and your doctor can make well-informed decisions about your treatment.  

How do I get my tumor tested?

If there is enough tissue from the original biopsy of your tumor, this tissue can be tested. If not, you may need a second biopsy or minor surgery to get enough tissue to test. Results are usually sent back to your doctor between one and three weeks later.

If your doctor doesn’t recommend tumor testing for you, it is okay for you to ask why not. Testing may not be appropriate in all cases, but it is best for you to know as much as you can about your disease so you and your doctors can be full partners in your care. If you have questions about the response you receive from your doctor, it is okay to ask for a second opinion from another doctor.
 

Talk to your doctor about genetic testing

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What if my test results don’t qualify me for targeted treatment?

Even if your tumor does not have known characteristics that can be matched to a targeted treatment that is available commercially or through a clinical trial, molecular testing can still help you and your doctor decide on the right treatment option for you.