Learning About Your Genetic Cancer Risk
In our previous post, we discussed the reasons for genetic testing and some pros and cons. Today, we’ll take a look at the process and what your results might mean.
Before you decide on genetic testing, it’s wise to talk with a genetic counselor, a person with special training in the field. This expert will review your personal and family medical history related to your cancer risk and explain what genetic testing can and cannot do. Because there are medical and psychological implications to learning your test results, they’ll help you think through whether testing is right for you.
It’s important to consider how the results might affect not only you, but also others in your family. The presence of a genetic mutation in one family member makes it more likely that other blood relatives carry the same mutation. Health discussions get complicated when some family members know their genetic status while others choose not to get tested. For example, if a woman learns that she has an inherited BRCA mutation, indicating an increased risk of developing breast or ovarian cancer, her mother, her sisters and her daughters may want to consider testing. A conversation with a genetics counselor can help family members better understand the complicated choices they may face.
You’ll also want to check with your insurance company before making a final decision about genetic testing. It’s important to know how much, if any, of the testing will be covered and how much you’ll be responsible for out-of-pocket.
How is Genetic Testing Done?
Testing is usually done through a simple blood draw. At times, it is done through a small sample of saliva or skin cells.
Until recently, most genetic testing for cancer focused on testing for individual inherited mutations. But, as more efficient and cheaper DNA sequencing technologies have become available, it’s become more common to conduct multiple-gene panel tests that look for many inherited mutations at the same time.
The sample is sent to a laboratory that specializes in genetic testing. After a period of several weeks, the lab returns the test results to the doctor or genetic counselor who requested the test.
What do the Results of Genetic Testing Mean?
The results of genetic testing aren’t always clear-cut. Results include the following possibilities: positive, negative, true negative, uninformative negative, false negative, variant of unknown significance or benign polymorphism. Let’s focus on negative/true negative and positive results.
Negative/True Negative Results
A negative test result means that the lab did not find the specific mutation that the test was designed to detect. A true negative result can show that you have not inherited the mutation that is present in your family and, therefore, that you do not have the inherited cancer syndrome tested for, do not have an increased genetic risk of developing cancer or are not a carrier of a mutation that increases cancer risk. A true negative result does not mean you have no cancer risk, but rather that your risk is probably the same as that of the general population.
Positive Test Results
A positive test result means that the lab found a specific genetic mutation associated with a hereditary cancer syndrome. A positive result may:
Confirm the diagnosis of a hereditary cancer syndrome
Indicate an increased risk of developing certain cancer(s) in the future
Show that you carry a genetic change that does not increase your own risk of cancer, but that may increase the risk for your children (if the child inherits two copies of the abnormal gene, one from their mother and one from their father)
Suggest a need for further testing
Provide important information that can help other family members make decisions about their own health care
If you have a positive test result indicating an increased risk of developing cancer in the future, you may be able to take steps to lower your risk and manage your health, including:
Lifestyle changes, such as quitting smoking, getting more exercise and eating a healthier diet to reduce the risk of certain cancers
Earlier, more frequent or more in-depth screening for cancer
Medication or preventive surgery (options for only a few inherited cancer syndromes)
Want to learn more? See these resources from the National Cancer Institute: