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Genetic Testing for Cancer

Genetic Testing for Cancer

Genetic testing is the use of medical tests to look for certain mutations in a person’s genes. Genes are pieces of DNA inside a body’s cells that tell the cells how to make certain proteins for the body to function. This DNA is passed down from parent to child and affects inherited traits like eye and hair color. Genes can also pass down traits that make it likely for a person to inherit certain diseases, like cancer. When changes (mutations) occur in these genes, this can play an important role in causing 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. Though the percentage of cancers related to inherited mutations is small (5-10%), genetic testing can help to determine how at risk a person is for certain cancer types, or to help with different treatment plans after a diagnosis.

Types of Genetic Tests

Predictive Genetic Testing

Predictive genetic testing is the type of testing used to determine if a person is at a higher risk of certain types of cancer based on inherited gene mutations. Inherited mutations, if they are present, are found in every cell, and can lead to a higher risk of cancer. Predictive testing might be advised if you have a strong family history of certain types of cancer to find out if you have the gene mutations that also put you at risk. Another reason might be if you have already been diagnosed with cancer if there are factors that suggest it might have been caused by an inherited genetic mutation. This can help determine what other cancers you might also be at risk for or may help your family members decide if they should be tested. You may also want this testing if your family member has the mutation so you can know to look for cancer early.

Genetic Changes Testing

While inherited genetic mutations are linked to a small percentage of cancers, most cancers come from acquired mutations. This means that a healthy cell changes due to either outside factors (like too much sun exposure, or smoking), or other unknown causes. Unlike inherited mutations, the mutations only happen in cancer cells, not in all cells in the body, and they will not be passed on to family members. However, there are cases where genetic testing is also helpful for cancers that have acquired mutations. Sometimes doctors will do tests on a sample of cancer cells to look for certain gene changes. These tests can give information on a person’s outlook (prognosis) and help tell whether certain types of treatment might be useful.

When To Get Genetic Testing

Genetic testing might be recommended if you or family members have certain types of cancers. Consider testing if you have any of the following:

  • Several first-degree relatives with cancer
  • Many relatives on one side of the family who have had the same type of cancer
  • A cluster of cancers in your family that are known to be linked to a single gene mutation. Examples include:
    • breast
    • ovarian
    • pancreatic
  • A family member with more than 1 type of cancer
  • Family members who had cancer at a younger age than normal for that type of cancer
  • Close relatives with cancers that are linked to rare hereditary cancer syndromes
  • A family member with a rare cancer, such as breast cancer in a male or retinoblastoma
  • Ethnicity
  • A physical finding that’s linked to an inherited cancer (such as having many colon polyps)
  • A known genetic mutation in one or more family members who have already had genetic testing

Outcomes of Genetic Testing

If you are considering genetic testing, there are benefits and potential drawbacks to consider. The biggest benefits are that testing can provide peace of mind, and an ability to plan. Genetic testing can cause peace of mind if you know family members have a mutation, and you have a negative test knowing you do not also have the mutation. Or, if a test comes back positive, knowing you have a mutation that could cause cancer can help you plan better for the future. For example, you’ll know to check regularly, get screened more often, and be able to learn about treatments that can help to reduce the risk of certain types of cancer. Furthermore, the earlier you can catch cancer, the more treatable it is.

It is also important to know that testing results also give limited answers. Testing is not able to tell you if you will get cancer, only if you have a higher risk of getting it. You can have a positive test, but never get cancer, and a negative result does not mean you’re at no risk for getting cancer. It is important to consider all factors when deciding to get genetic testing.

Genetic Testing and Clinical Trials

Clinical trials for cancer patients offer access to treatment options that are not widely available. Massive Bio guides patients through the most comprehensive clinical trial matching process. Participating in a clinical trial provides access to new studies that are not yet widely available. Many clinical trials require genetic testing for trial eligibility. If you want to learn more about these treatments, you can consult the team at Massive Bio.

Dr. Arturo Loaiza-Bonilla, MD
Cofounder & Chief Medical Advisor

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