Chapter 4 - Genetic Testing and Counseling

Hope is the thing with feathers that perches in the soul,
and sings the tune without the words,
and never stops at all.

— Emily Dickinson.

More and more, cancer genes—especially breast cancer genes—and genetic tests are in the news. It can be difficult to make sense of the dizzying array of scientific discoveries and what they mean to you. Do you think you have a family history of breast cancer? Should you consider a genetic test for breast cancer? What happens when you have a genetic test? Will it tell you if you’re going to get breast cancer?

In this section, we provide answers to some of the most common questions about genes, breast cancer, and genetic testing. We’ll begin with the basics.

What is a gene?

Genes are pieces of DNA that are passed down from parent to offspring. DNA is the chemical material inside our cells that makes instructions to run the body. Each gene contains instructions to make a certain product for the cell. There are approximately 25,000 genes in each cell of the human body.

Genes influence how our bodies function and grow. They determine other characteristics about us such as the color of our hair and eyes. Human genes come in pairs. One set of genes is passed down (or inherited) from the mother, and the other set is passed down from the father.

How do genes relate to breast cancer?

Most cancer occurs by chance and is not due to an inherited or single environmental cause. If a gene contains a mistake (or mutation), it may not work properly. In fact, we all have several mutations, many of which cause no harm. However, certain mutations can increase the risk for illnesses such as cancer.

All mutations are either passed down from parent to child (inherited mutations), or happen during a person’s lifetime (sporadic mutations). The great majority of breast cancers are due to sporadic mutations.

Sporadic gene mutations are caused by the body’s response to stresses in the environment, such as chemicals, radiation and hormones. Usually, the body can fix these errors before they cause problems. However, over a long period of time, they may add up and result in diseases such as breast cancer. This is why people tend to develop cancer later in life.

What are breast cancer genes?

Scientists have found a number of genes that affect breast cancer risk. When mutated, these genes can lead to a greater risk for breast (and ovarian) cancer and can be passed down from generation to generation. Most cases of inherited breast cancer are related to two genes: BRCA1 and BRCA2.

The role of the BRCA genes in the body is to keep cells growing at a controlled normal rate, and not too quickly. A mistake (or mutation) in a BRCA gene can allow cells to grow and divide unchecked, resulting in cancer.

Scientists believe that about 5 - 10 percent of breast cancers are associated with inherited BRCA1 or BRCA2 mutations. This means that the vast majority of breast cancers (90-95 percent) occur by chance and are not associated with any currently known genetic mutations.

What are the risks for a woman who carries a BRCA mutation?

A woman with a BRCA1 or BRCA2 mutation is much more likely to develop breast and ovarian cancer than a woman without a mutation. Scientists estimate that the risk to develop breast cancer over her lifetime (by age 70) is up to 87 percent (compared to the general population risk of about 13 percent). The risk to develop ovarian cancer is estimated to be up to 56 percent over a woman’s lifetime (compared to 1.7 percent). Not every woman who has a mutation in a BRCA1 or BRCA2 gene will get breast or ovarian cancer. It is difficult to say what the exact risk of breast cancer is, but it depends on gene factors and age.

What is a genetic test for breast cancer risk?

When a person has a genetic test for breast or ovarian cancer, a small sample of blood is drawn. Two genes (BRCA1 and BRCA2) are examined to see if they contain mutations that could increase a woman’s risk for breast cancer.

What do the results of a genetic test for breast cancer risk mean?

Genetic testing for any disease risk is a more complex issue than it may at first seem. Testing for breast cancer risk is more than simply a “yes” or “no” answer, and it is far from an exact science. Due to the complexities of genetic testing, it is important for your test result to be interpreted by a professional experienced in genetic testing, such as a genetic counselor.

• A positive result means that a woman has a BRCA mutation that is known to increase the risk of developing breast or ovarian cancer. However, a positive result does not mean that a woman will definitely develop breast or ovarian cancer.
• A negative result usually means that a woman does not have a known BRCA mutation. There is a small chance that a negative test result means the test did not find a mutation when, in fact, a woman actually does have one.
• In a small percentage of cases (about 5 percent) the genetic test for breast cancer risk returns an
uninformative, ambiguous or vague result.

Other points to consider about genetic testing for breast cancer risk include:

• A family history tree or “pedigree” should be drawn by a genetic counselor, geneticist or healthcare provider to help determine if the breast cancer is inherited.
• A family member who has had breast cancer should be tested initially to identify more accurately the gene mutation. Then, other family members can be tested for the known mutation more reliably and at a lower cost.
• The father’s family history is important in assessing breast cancer risk because altered BRCA genes can be passed down on the father’s side as well.
• Genetic information applies not only to the person having the test, but also to family members and the person’s children.

For these reasons and others, it is important for people considering genetic testing to talk to a genetic counselor. Genetic counselors for cancer risk in North Carolina usually work in genetics clinics in large hospitals or comprehensive cancer centers. Genetic counselors are trained to recognize patterns of inherited disease in families and to counsel patients about the specifics and pros and cons of genetic testing. (See our list of Cancer Genetic Risk Clinics in North Carolina at the end of this section).

When should someone consider genetic counseling or testing?

This is an individual decision. However, if a woman has a significant family history of breast cancer (see Who is More Likely to Have a BRCA1 or BRCA2 Mutation?), she may benefit from genetic counseling and, in some cases, genetic testing. If a woman is worried about her risk, genetic counseling may reassure her.

If a woman has a BRCA gene mutation, what can she do?

If you are at increased risk for breast or ovarian cancer, you can make choices that will help reduce your risk of getting cancer, or help find cancer early. Of course, you can take these steps with or without getting tested for a BRCA1 or BRCA2 alteration.

• Increase screening. You may choose to be monitored more closely for any sign of cancer. This may include more frequent mammograms, breast exams by your doctor, breast self-exams, and an ultrasound exam of the ovaries. Breast MRIs have also been shown to be effective in detecting breast cancer in high-risk women.
• Consider preventive drug therapy. You may choose to take one of a few drugs that are known to reduce the risk of developing breast cancer. As with all drugs, these have side effects that must be balanced with the benefit of taking such a drug. Talk to your healthcare provider or oncologist for more information.
• Join a research study. Because it is not yet possible to prevent cancer, you may choose to join a research study aimed at developing better screening measures or to identify new ways to reduce cancer risk.
• Make healthy lifestyle choices. Some research studies have shown that physical activity and other lifestyle factors such as avoiding obesity can reduce breast cancer risk in BRCA mutation carriers.
• Consider prophylactic (preventive) surgery, during which your healthy breasts and/or ovaries are removed. These surgeries are the most effective way to reduce your risk of breast or ovarian cancer, but they are a more drastic option.

What are possible benefits of genetic testing for breast cancer risk?

• A genetic test may help you make more informed medical decisions and lifestyle choices.
• Knowing the results of a genetic test may help you better cope with your cancer risk, and help you decide whether or not to have preventive drug therapy or surgery.
• The genetic test may give your family members useful information, and it is important to share the results. You may want to know the results for your children’s sake.
• A genetic test may reduce feelings of uncertainty.
• A genetic test may give your physician more information to decide on treatment recommendations.
• A positive result may increase your likelihood of keeping up with recommended screening (mammograms, breast exams, etc.) on a regular basis.
• A negative result may relieve some anxiety for you and your children by knowing that you most likely do not have an altered BRCA gene.
• A negative result may help you avoid extra screening for breast cancer.

What are potential disadvantages of genetic testing?

• The result of genetic testing does not eliminate uncertainty. A positive test does not predict that a person will get breast cancer— only that a person is at increased risk. Also, a negative test does not mean that a person will never develop breast cancer.
• Genetic tests can be expensive, and they may or may not be covered by a person’s insurance.
• There is no proven way to reduce cancer risk completely in persons who test positive.
• There is no guarantee that test results will remain private.
• Genetic testing can have a psychological impact. If you test positive, you could experience negative feelings such as fatalism, anxiety, decreased self-image, depression, shame, or blame. If you test negative, you may feel guilt that you have been “spared” if other family members test positive.

Why is genetic counseling important?

As you can see from the above description of genetic testing for breast cancer risk, this type of test is not just a simple blood test. It is a complex issue. It is a good idea to see a genetic counselor before considering genetic testing.

Genetic counselors have been trained in genetics and genetic testing and can advise their patients about whether they should consider a genetic test. They can explain the basics of the test, as well as how the test is interpreted, and its benefits and limitations. They can take a family history (or pedigree) to see whether a person would be a good candidate for genetic testing.

Genetic counselors usually work at large hospitals that have genetics centers. They may charge for a consultation, and they can help to verify insurance coverage before undergoing counseling or testing. Coverage will vary from policy to policy. See our listing of Cancer Genetic Risk Clinics at the end of this section to find these hospitals and phone numbers to call in North Carolina.

What is the difference between a geneticist and a genetic counselor?

A geneticist is usually an MD who specializes in genetics. Genetic Counselors generally are not MDs, but have a two-year Masters degree in a genetic counseling program.

Be prepared with information.

One piece of information that may help to determine whether you could have a hereditary risk for breast cancer is your family’s history of cancer. A pedigree shows your family’s history of cancer. For your healthcare provider or genetic counselor to draw a pedigree, you will need to know the kinds of cancers that your relatives had, the ages at which they had cancer, and whether any female relatives were diagnosed with breast cancer before or after menopause (usually around age 50).

Take your time. Gather as much information as you need. You are the best judge of deciding what is right for you.

Portions of this section were adapted from National Cancer Institute educational publications about genetics and breast cancer (800.4.CANCER or www.cancer.gov).