Genetic Testing for Cancer: What It Can (and Can’t) Tell You

When you catch a cold, you know how it happened: You came in contact with a cold virus. Cancer, though, seldom has such an obvious cause. A diagnosis may cause you to speculate on why it happened: Did I eat too much red meat? Was it fumes from that factory nearby? Didn’t my grandmother have cancer, too?

Doctors can’t always identify what caused someone to get cancer, but genetic testing for cancer can be a helpful tool, especially for cancers related to genetic mutations, or changes, that can be passed from parent to child. These gene mutations don’t always cause cancer, but they can increase your cancer risk.

Genetic testing has benefits and limitations, and in this blog, we’ll discuss what it is, when you may need it, and how it can and can’t provide the answers you’re looking for.

Gene Mutations That Increase Cancer Risk

Researchers believe about 10% of cancers result from genetic changes passed down through family members, such as a parent or grandparent. These changes don’t automatically cause cancer, but they make cancer more likely, often by altering how cells grow, divide and repair themselves.

For instance, two genes, BRCA1 and BRCA2, contribute to DNA repair, and mutations in these genes may affect their ability to prevent cells from becoming cancerous. BRCA1 and BRCA2 mutations increase your risk of developing breast cancer, along with many others, including ovarian, prostate and pancreatic cancers.

Inherited cancers can also be associated with syndromes, or disorders, that cause certain cancers to run in families. These syndromes include hereditary breast and ovarian cancer syndrome, familial adenomatous polyposis syndrome (colorectal and other cancers) and Lynch syndrome (colorectal, uterine and other cancers).

The following types of cancer may be related to gene mutations that increase your risk:

For these and other cancers thought to have a genetic component, genetic testing can provide actionable information to help you stay on top of your health outlook.

What Qualifies You for Cancer Genetic Testing?

Your personal cancer history and your family medical history help determine whether you need cancer genetic testing. The National Cancer Institute recommends that people who have had these cancers be tested for inherited cancer risk:

Colorectal cancer before you turn 50
Endometrial cancer before you turn 50
Ovarian cancer
Pancreatic cancer
Prostate cancer that spreads (metastatic cancer)
Female breast cancer diagnosed at age 50 or younger, triple-negative breast cancer at any age or male breast cancer at any age

In addition, your family history might indicate an inherited cancer syndrome. You may benefit from genetic testing if:

A family member was told they had genetic changes related to cancer risk.
A family member developed multiple different cancers.
Several family members had the same kind of cancer.

Your family ethnicity is also associated with a higher cancer risk. For example, women of Ashkenazi Jewish descent have a higher risk for breast cancer due to the higher prevalence of founder mutations (disease-related gene changes that occur in specific groups of people with a shared ancestry) in the BRCA1 and BRCA2 genes in this population.

How Genetic Testing for Cancer Works

The genetic testing process typically starts with genetic counseling. A certified genetic counselor reviews your personal and family health history, then gives you an assessment of your risk of developing cancer and the likelihood that there is hereditary cancer in your family.

Once they’ve discussed their findings with you, they’ll discuss the benefits and drawbacks of genetic screening. After that, the decision to have genetic testing for cancer is up to you—it is an individual decision.

If you decide to move forward, a small sample of your blood or saliva will be collected and sent to a laboratory for testing. You will typically receive your results within two to three weeks.

Cancer genetic counseling and some types of genetic tests may be covered by health insurance. You will need to ask your insurer to find out what qualifies you for coverage. Your genetic counselor can also review this information with you.

Interpreting Your Results

If you proceed with genetic testing, your genetic counselor will review the results with you. You’ll also want to share your results with your healthcare provider. They can tell you what steps you need to take based on your inherited cancer risk.

Your results can inform both prevention and treatment decisions. For example, if you’re at higher risk for colorectal or breast cancer, your doctor may suggest more frequent or earlier screenings. Women with higher breast cancer risk may need to get a breast MRI every year in addition to traditional mammography.

When it comes to treatment, cancers with certain genetic variants respond best to specific targeted therapies. This knowledge, along with tumor testing and precision medicine, can help your doctors identify the most effective treatments for your cancer.

Benefits and Limits of Genetic Testing for Cancer Risk

While cancer genetic testing can tell you about your inherited likelihood for developing certain cancers, it cannot tell you definitively that you will or will not get cancer. Consider the following benefits and limitations as you make your decision.

Limitations

Depending on your approach to managing your health, genetic testing for cancer can have financial and emotional costs:

Cancer genetic testing may not be covered by insurance.
Follow-up testing and cancer screenings, if needed, may require additional time and expense.
If your results are positive, you may have fears about developing cancer or passing your risk down to your children.
If your results are uncertain, you may experience stress and ongoing anxiety.
Although extremely unlikely, genetic tests can have false-positive or false-negative results.

Also, genetics and family history aren’t the only cancer risk factors. Your environment and lifestyle choices play an important part in determining your likelihood of getting cancer.

Benefits: Knowledge Is Power

For many people, though, both negative and positive results have their benefits. A negative test may mean peace of mind, especially if you were worried that cancer seems to run in your family.

On the other hand, a positive test empowers you to protect yourself as much as possible. You and your doctor can discuss additional screenings or lifestyle changes that can lower your risk. When you know you have an inherited cancer risk, you can also protect your family by advising them to ask their doctor about steps they need to take.

In Conclusion

Cancer genetic testing is a personal decision, but it can inform you of your inherited risk for certain cancers. Your journey begins with genetic counseling to discuss the benefits and risks associated with the test. If you proceed with testing, the test itself involves taking a small sample of blood or saliva and having it analyzed for gene mutations. You should discuss your results with your doctor.

For many people, the benefits of genetic testing for cancer outweigh any drawbacks. Knowing about your inherited risk empowers you to:

Make lifestyle changes and schedule screenings to keep yourself safe
Protect family members by sharing valuable information with them

If you have further questions, the genetic counselors at Capital Health will gladly talk through your decision with you.

Concerned about your inherited cancer risk? Schedule a consultation with the Capital Health Cancer Genetics Program.