Hereditary Mutations: Are You at Risk?
Your body is always changing. If you have gray hair or stretch marks, you've probably noticed how your body can change. You may not always notice other ways that your body can change, however. For example, your body's cells constantly change, dividing and creating new cells. You might not notice it when, as your cells divide and copy their DNA (their genetic information), a mutation is introduced.
A mutation is when a cell makes a mistake in copying its DNA for the new cell. Over time, mutations can be introduced to your cells' DNA. These mutations can contribute to the development of cancer. Some of these mutations can be inherited, passed down from generation to generation. Some of these changes can lead to certain types of cancer. These so-called hereditary mutations can also put people who have had cancer at a greater risk for getting another cancer. Hereditary mutations account for about 5 to 15 percent of all cancers.
Cell Mutations
There are two types of cell mutations, acquired and hereditary.
Acquired mutations occur when a cell's DNA is damaged over time due to environmental influences. These can include cigarette smoke, sun exposure, radiation exposure, and toxins. Cancer treatments, such as radiation and chemotherapy, can also cause acquired mutations. Most cancers have acquired mutations in them.
Hereditary mutations occur when a cell's DNA carries a change that has been passed down from the person's mother or father. This mutation is due to heredity. People with hereditary mutations have that mutation in all of their cells for the rest of their lives. Just as they inherited the mutation from one of their parents, they can pass down this mutation to a son or daughter.
Someone is at risk for having a hereditary mutation if more than two relatives in their immediate family (parents or siblings) have had cancer and:
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if these family members had cancer at a young age.
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if they had certain types of rare cancers, such as male breast cancer or medullary thyroid cancer.
Second Cancers
According to Ellen Matloff, MS, if you've had cancer, you could get it again if you have a hereditary mutation. Matloff is associate research scientist and director of the Cancer Genetic Counseling Program at Yale Cancer Center.
"Even if someone with a hereditary mutation had a cancer, survived the cancer, and had been treated for it, they still have that mutation in many other cells of their body, and can develop a second cancer," she said.
It's important to understand that a second cancer is when a new tumor develops. A second cancer is not a recurrence of the first cancer. An example would be if you had Hodgkin's disease, were treated for it, and then developed breast cancer. Hodgkin's disease does not spread to your breasts; therefore, the second cancer is unrelated to the first cancer. A recurrence is when the cancer was never cured and it redevelops in the same part of the body or it spreads (also called metastases) to another part of the body. An example of a recurrence would be if you had breast cancer and it spread to your bones. The cancer cells now in your bones are breast cancer cells. The bone cancer would be called bone metastases since the breast cancer spread to your bones. You could also refer to this cancer as metastatic breast cancer.
Genetic Counseling
Whether you have cancer or not, it's always important to review your family health history. This lets you see which diseases or conditions, if any, tend to run in your family. Matloff suggested that people get genetic counseling if they think they might have a hereditary mutation. Then, they can decide if they would like to have genetic testing.
Genetic counseling is when an individual or family meets with a professional familiar with genetic testing. This may be your doctor, an advanced practice nurse, a social worker, or someone who is trained as a genetic counselor. During counseling, you will learn about the role of genetics, heredity, and risk. You will also have a chance to ask questions about genetics and genetic testing. In addition, your counselor will prepare a family pedigree and review informed consent with you.
What's Your Pedigree?
A family pedigree is like a family tree of your family's medical history. The pedigree includes information about your maternal and paternal medical history, ancestry, and ethnicity. To get information for a complete family pedigree, your counselor may need to speak with family members. If your family pedigree suggests that you may be at risk for a hereditary mutation, your counselor will suggest genetic testing.
Informed Consent
Many genetic counseling sessions include signing an informed consent form. This legal document states what will happen during genetic testing so that the provider and patient are both clear. Some counseling programs include a second informed consent before the patient learns the results of the genetic test. This lets the person receiving the test results change his or her mind about receiving them. And, after the test results are given, sometimes a third informed consent is given. This involves sharing test results with family members.
Genetic testing is controversial because of the emotional and ethical ramifications associated with it. Some people fear discrimination from their insurance company or employer if they test positive for a genetic mutation. Others fear being ostracized or avoided by family and friends. And some people feel guilty for carrying a genetic mutation. During genetic counseling, the counselor will talk to you about how you could react to the test results and other concerns or issues you may have. Whether you choose to have a genetic test or not, there is other important information to learn from the genetic counselor, such as how to prevent or find cancers early when they are easier to cure.
Matloff described how genetic testing could be a life-changing test. "Genetic testing is a process that affects not only the patient's risk, but the risk to his or her children, siblings, parents, and extended family members," she said. "It is an emotional process. It should not be approached casually without full informed consent and genetic counseling. This is not just another blood test."
This Is a Test
After counseling, if you decide to have a genetic test, you will have a blood test. Then, you will have to wait 4 to 12 weeks for the results. About half of the people who have genetic counseling go on to have genetic testing.
It's important to remember that a positive test result does not mean that you will definitely get cancer. And, a negative test result does not mean that you will never get cancer.
"A genetic test tells you what might happen, not what will happen," said Matloff.
Genetic counseling usually includes a post-test-result session. This may happen the same time you get the test results or it could be a separate session. At this session, you will talk about the results and how to cope with them.
If your test results, positive or negative, upset you, seek help. Matloff said, "A referral to a psychologist to examine these issues in depth is often a good investment of time and energy."
Reduce Your Risk
If you have a hereditary mutation, there are some ways you can reduce your risk of getting cancer. Part of Matloff's job as a genetic counselor is to tell people what they can do to reduce their risk of getting cancer.
Increase surveillance. Matloff said that if you've never had cancer and you have a hereditary mutation, tell your doctor. This way, your doctor will be aware that you could be at an increased risk of developing cancer and increase his or her surveillance of you.
Chemoprevention. This is when your doctor gives you medicine to reduce your risk of developing certain cancers. "Depending on the type of cancer it is," said Matloff, "we can offer some form of chemoprevention for the cancers for which [a person] is at risk. For example, a woman has ovarian cancer and learns that she has a BRCA1 mutation, a breast and ovarian cancer gene mutation. She may be offered tamoxifen to reduce her risk of developing breast cancer."
Tissue or organ removal. With this aggressive option, the person at risk decides to have his or her tissue or organ that is at risk removed before the cancer develops. Matloff said, "I saw a family with a risk of gastric cancer. Several members of the family said that if they carried the mutation, they would be willing to have their stomachs removed. This is a drastic measure, but it is chosen by some family members."
Another example would be if a woman with a strong family history of breast cancer decided to have a double mastectomy to reduce her risk of developing it.
While these options can offer relief from getting cancer or a second cancer, it is important to remember that just because you tested positive, you may not get cancer at all. And, if you tested negative, you could still get cancer, although it probably won't be caused by a hereditary mutation. Keep in mind that whether you have had cancer before or not, 85 to 95 percent of cancers are not caused by known hereditary mutations.