Genetic Testing for Breast Cancer

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If you have immediate relatives who've been diagnosed with breast cancer (and, potentially, some other cancers), it's worth talking to your doctor about genetic testing to determine if you carry a genetic mutation that increases your risk of the disease. Genetic testing can also be beneficial to those who have already been diagnosed with breast cancer, regardless of family history.

Almost 10% of all breast cancers diagnosed in the United States are related to genetic mutations. Some genetic mutations are inherited, while others are somatic, meaning that they are due to gene changes over the course of one's lifetime that don't get repaired.

Gene Mutations Related to Breast Cancer

Women and men who have mutated versions of the BRCA1 and BRCA2 genes are at higher than average risk of developing breast cancer. These genes are also associated with a greater risk of pancreatic and prostate cancers, as well as ovarian cancer; having a close relative with ovarian cancer, in particular, raises concern about a heightened risk for breast cancer.

As genetic research progresses, scientists are finding other genes that indicate risk for breast and other cancers, as well as benign conditions. Other genes that may be associated with breast cancer include ATM, BRIP1, CDH1, CHEK2, MRE11A, MSH6, NBN, p53, PALB2, PTEN, RAD50, RAD51C, STK11, and TP53.

Some tests focus on a specific area of one gene to look for a mutation, while others analyze an entire gene. Panel tests, as they're called, look at a set of genes for mutations. These tests can include as few as two genes or as many as 25 to 30.

In a clinical setting, the tests are done on a blood sample; genetic counseling is typically recommended, as results can be life-changing.

Motivations for Genetic Testing

People who are concerned about their risk of breast cancer due to relatives' diagnoses may want to visit a genetic counselor to discuss their family health history, as well as other factors, to determine if a genetic test would be helpful.

High-risk groups include people with:

  • Ashkenazi Jewish ancestry (Eastern and Central European)
  • One or more BRCA-positive relatives, female or male
  • Breast cancer in two or more close relatives (immediate family)
  • Family members diagnosed with breast cancer before age 50
  • An immediate family member with cancer in both breasts
  • Several family cases of ovarian cancer

If you've already been diagnosed with breast cancer, a blood sample can be tested so your doctor can design the most effective, timely, and appropriate treatment to kill your cancer and prevent a recurrence.

For example, the BRCA1 mutation means you're more likely to develop triple-negative breast cancer, which is a type that doesn't respond to hormone therapy or certain types of cancer drugs. However, it's more likely than some types of cancer to respond well to chemotherapy.

Genetic testing may be done for several reasons, including to:

  • Determine if you have the mutated BRCA genes
  • Evaluate choices for prevention
  • Customize treatment options
  • Avoid over- or under-treatment
  • Reduce side effects of treatment
  • Get proper treatment for preventing a recurrence

Making the Decision

If you've already been diagnosed with breast cancer, getting tested—if recommended by your doctor—is advisable for the above reasons.

But if you don't have breast cancer, this decision can be a bit harder to make. While knowing if you've got the BRCA genes can be empowering for some women, it may trigger anxiety and fear in others. That is, if you test positive, you may worry about a future breast cancer diagnosis (which may or may not come).

You may want to consider holding off on getting tested if you think testing positive will be too hard for you emotionally.

Cost

Full sequencing of both BRCA genes, which checks for any mutation that could occur amongst them, costs about $2,400. Testing for just the three most common BRCA mutations costs about $650.

Medicaid does not cover the cost of the test. If you are insured, coverage will depend on your provider and plan.

If finances are a concern, you might consider at-home testing. These options cost between $295 and $1,200; you may be able to flexible spending account (FSA) dollars, if you have them. Some insurers may cover a clinical genetic test if an at-home kit yields a positive result.

DIY Tests: Important Considerations

Do-it-yourself genetic test kits are convenient and more affordable than clinical tests, but it's important to know they are not as reliable as a laboratory test. Labs used by medical professionals must follow federal regulations regarding testing procedures, quality control, and staffing, and the same does not apply to these kits. The U.S. Food and Drug Administration (FDA) cautions that at-home tests should not be considered substitutes for being assessed by your doctor, and DIY results should always be clinically confirmed.

Results

If you decide to go ahead with a genetic test, your doctor can order it for you. You'll give a blood or tissue sample that will be sent to a special lab for testing. Results will be returned in four or five weeks, and you'll likely meet with a genetic counselor to review and discuss what the test found.

You will also get a written summary of your test results. Make sure you understand your results and options for prevention or treatment.

If you test positive for an abnormal BRCA1, BRCA2, or PALB2 gene and you have never had breast cancer, it means you are at much higher-than-average risk of developing it over the course of your lifetime.

The average lifetime risk of breast cancer for women is about 12%.

  • For women who have a BRCA1 or BRCA2 mutation, the risk is between about 69% and 72%. Lifetime risk of ovarian cancer is 17% to 44%, versus just under 2% for the general population.
  • Women with an abnormal PALB2 gene have a 33% to 58% lifetime risk of developing breast cancer.

Furthermore, having an abnormal BRCA1BRCA2, or PALB2 genetic test result means there is a 50% chance you can pass that mutation on to your children.

It's also important to know what testing negative doesn't mean that you won't go on to develop breast cancer; it's possible you have another related mutation that is not yet known or tested for. In addition, other factors unrelated to genes may affect your risk, such as age and menopausal status.

Telling Your Loved Ones

Receiving a positive test result will most likely have an emotional impact, not just on you, but on other members of your family (if you choose to tell them). They may be concerned about your health, but also their own, if they are blood relatives.

You may want to urge your family members to get tested and invest in breast cancer prevention strategies, but remind yourself that each person will process this information differently and make the decision that is right for them.

Next Steps

What you do with your results will depend on whether or not you have already been diagnosed with cancer, your doctor's recommendations (based on your overall health, age, and history), and your personal wishes.

Monitoring and Prevention

You may need no other follow-up than to remain vigilant and be sure to have regular mammograms and perform breast self-exams to increase the likelihood of early detection.

Positive results may motivate you to be more dedicated to changing modifiable breast cancer risk factors, such as:

Prophylactic Measures

On the other hand, you may take testing positive for BRCA1 or BRCA2 as a major call to action (the same goes for your doctor). Knowing that you have even some elevated risk of breast cancer may be enough to begin using hormonal therapies or seek a prophylactic mastectomy to remove your breasts before the disease has an opportunity to strike.

Hormonal Drugs

Four different hormonal therapy medicines have been shown to reduce the risk of hormone-receptor-positive breast cancer in high-risk women. Two are selective estrogen receptor modulators (SERMs) and two are aromatase inhibitors. They are:

These drugs all have side effects and risks associated with them, so talk to your doctor about which one may be best for you and carefully weigh the risks against the benefits.

It's important to note that these drugs do not lower your risk of developing breast cancer that is hormone-receptor-negative.

Surgery

Some women who test positive choose to have a preventative double mastectomy to lower their risk of developing breast cancer. Surgical removal of both breasts seems extreme to some, but to others, it represents peace of mind.

Surgical breast removal decreases the risk of breast cancer by about 90%. Preventative removal of your ovaries and fallopian tubes (oophorectomy) can further reduce your breast cancer risk as long as you're not menopausal.

Surgery comes with its own risks and costs, so this is not a decision to enter into lightly. Speak with your doctor about all of your options and talk over your choice with your loved ones.

That said, while other people may have strong opinions about what you should do, it's your body and your health. You're the one who has to be comfortable with whatever choice you make.

If You've Already Been Diagnosed

Your test results can influence your treatment plan if you've already been diagnosed with breast cancer. By knowing the mutations that are paving the way for cancer cell growth, your oncologist can narrow down the options that are best suited for your genetic profile.

For example, your doctor may suggest drugs such as PARP inhibitors, which have been found to "arrest the growth of cancer cells that have BRCA1 or BRCA2 mutation," according to the National Cancer Institute.

Genetic Discrimination

You could, conceivably, face discrimination based on your genetic test results when you apply for life insurance or a job, but so far this hasn't been a major problem

The Genetic Information Nondiscrimination Act (GINA) was signed into law in 2008, protecting most Americans against discrimination based on their genetic information when it comes to health insurance and employment.

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