9 common questions about genetic testing for cancer | Way of life
Your genes play a role in almost every area of your health. A gene is like an instruction manual for your body that tells your body how to function, grow, and stay healthy. People have about 20,000 genes in their body.
Many health problems have a genetic link. Genetic testing can help you and your healthcare team understand if you have an increased risk of developing certain conditions that run in your family. If you are at risk, you may be able to take preventive measures to reduce your risk or undergo genetic testing to clarify your risk.
Here are nine common questions about genetic testing:
Do all types of cancer have a genetic component?
Most cancers are considered sporadic, meaning the cancer occurs randomly or has environmental influences, such as smoking and lung cancer. About 25% of cancers are considered familial. This is when several members of a family are affected by cancer. These family members have common genetic factors in combination with common environmental factors that lead to the development of these cancers.
About 10% of cancers are considered hereditary or have a single specific genetic component that can be tested for and increase the risk of developing cancer. Genetic counseling and genetic testing can help determine which category a person’s individual or familial cancer belongs to. It can also help estimate your risk of developing cancer.
What types of genes are examined in genetic testing?
You may have an increased risk of certain health problems, including certain types of cancer, depending on your genes. A genetic test looks for specific harmful genetic changes, called pathogenic mutations or variants, that can cause you to develop a genetic disease. Genetic changes are like misspellings in your body’s instruction manual.
Most genetic tests look for changes in a group of genes called a panel. However, tests can look for changes in a single gene when there is a known genetic mutation in your family. The genes most commonly associated with cancer risk are BRCA1 and BRAC2. These genes are associated with breast and ovarian cancer. It is known that changes in other genes can also increase the risk of these cancers.
There are also gene panels that assess the risk of other cancers, such as colorectal, pancreatic, prostate, liver, uterus, and endometrial cancers.
Am I guaranteed to get cancer if I have a known gene?
No. Inheriting a harmful genetic change means you have an increased risk of cancer, but it does not guarantee that you will develop cancer in your lifetime.
If tests show you have an increased risk of cancer, you may need to be screened earlier or more often. For example, if you have a change in the BRCA gene that increases your risk of breast cancer, your healthcare team will recommend that you have mammograms or breast MRI scans at a younger age or more frequently. The genetic counselor will explain your associated cancer risks and screening recommendations based on your genetic test results.
What criteria must I meet to perform a genetic test?
Your health care team may recommend genetic testing based on guidelines set by the National Comprehensive Cancer Network (NCCN). These guidelines use factors such as your personal history of cancer, your family history of cancer, your ancestry, or the presence of abnormal cells to determine if you are eligible for genetic testing.
If you don’t follow the NCCN guidelines, you can still proceed with testing. Your health insurance may not cover all or part of the test costs, so more out-of-pocket costs to be tested are possible.
Can genetic testing help during cancer treatment?
If you’re battling cancer, genetic testing can help your healthcare team make recommendations about treatments and surgeries. For example, some cancers associated with genetic mutations respond better to certain types of chemotherapy treatments. Likewise, genetic testing can help you decide between a lumpectomy or a mastectomy when making surgical decisions about breast cancer. It may also affect the management of cancer risk over time.
The results can also help other family members. Potentially, your children, siblings, nieces and nephews could have inherited the same genetic mutation. Knowing this information can help them establish early screening schedules and make healthy decisions about their lives.
How can I prepare for a genetic screening consultation?
Taking a detailed family medical history is the most important thing to prepare for a genetic counseling appointment. Try to collect information about relatives, including types of cancer diagnosed, age at diagnosis, current age, or age at death. Also find out if any members of your family have already undergone genetic testing.
If no genetic testing has been done before, the best person to test is often the family member with cancer. This person is more likely to have a genetic change, if there is one. If an affected family member is unavailable for testing due to death or lack of interest, an unaffected person can still be tested.
Another thing to think about before your consultation is the purpose of your test. Younger patients usually want to know their personal risk so they can do further screening. Older patients who have survived cancer may wish to gather information and share it with downstream family members so that they are aware of harmful genetic changes they may have inherited.
Am I only capable of getting cancer if I have the BRCA gene or one of these other genes?
A common misconception is that you either have one of these genes or you don’t. Everyone has the BRCA genes and these other genes associated with cancer risk. The role that these genes play in the body is to prevent the onset of cancer.
It’s when a harmful change occurs in one of these genes that it doesn’t work as it should. This leads to an increased risk of developing cancer.
People without these harmful changes can still develop cancer, but the risk is not as high as someone who has an inherited predisposition.
Am I more likely to inherit something from a parent of the same sex as me? Or the parent I most resemble?
No. Each person has two copies of each gene – one copy inherited from each parent. If a parent has a harmful genetic change in one copy of a gene, the copy it will pass on to children is random.
Every child has a one in two chance of inheriting the typical copy or the altered copy, regardless of your biological sex or that of your parents, or whether you are more like one side of the family.
There is breast cancer on my dad’s side of the family, I’m not at risk because my dad can’t pass it on, right?
People often think that a hereditary risk of certain cancers, such as breast and ovarian cancer, cannot be transmitted by men. It’s not true.
All people, regardless of their biological sex, can carry an inherited risk factor for any type of cancer and can pass it on to any of their children.
Although you cannot change your genes, you can control certain aspects of your environment, such as diet and level of physical activity, as well as alcohol and tobacco consumption. That’s why it’s still so important to lead a healthy lifestyle, regardless of your personal and family genetic background.
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