Key points
- Genetic testing is recommended if you have had colorectal (colon) or uterine (endometrial) cancer and have abnormal tumor screening results.
- Your genetic counselor or other healthcare provider might recommend genetic testing based on your personal and family health history of colorectal, uterine, and other cancers and whether you have a family member diagnosed with Lynch syndrome.
Why get tested
Genetic testing for Lynch syndrome can confirm your diagnosis if your tumor screening results (Immunohistochemistry (IHC) or microsatellite instability (MSI)) are abnormal. Finding out that you have Lynch syndrome can help you better understand and manage your risk for colorectal (colon), uterine (endometrial), and other Lynch syndrome-related cancers. Your healthcare provider can help you decide what cancer screenings and other medical treatments you need to prevent cancer or find it early and when to start.
If you have genetic testing based on your family health history and testing shows that you did not inherit the genetic change that runs in your family, you might not need to have screenings beyond what is recommended for the general public. Genetic counseling before genetic testing based on personal and family health history of colorectal, uterine, and other cancers is important to determine whether you and your family are likely enough to have Lynch syndrome that it is worth getting tested.
Who should be tested
Usually, genetic testing will be recommended if
- Your tumor screening results (IHC or MSI) are abnormal
- You have had colorectal cancer
- You had uterine (endometrial) cancer before age 50
- You have had multiple primary cancer diagnoses
- Several family members have had cancers related to Lynch syndrome
- You have a family member with Lynch syndrome
Lynch syndrome-related cancers
How testing works
Genetic testing looks for inherited genetic changes (mutations) that cause Lynch syndrome. Your healthcare provider may recommend a multigene panel, which looks for genetic changes in several genes at the same time, including the genes associated with Lynch syndrome.
The genetic counselor can help to determine the best testing strategy for you and your family. When possible, testing should start with someone in the family who has had cancer.
Testing results
Interpretation of genetic test results may vary, depending on whether you have had colorectal cancer in the past or not.
If you have already had colorectal cancer
If you have already had colorectal cancer or another Lynch syndrome-related cancer, here's what the test results mean for you and your family:
Positive test result
You have a genetic change known to cause hereditary colorectal cancer.
What it means for you
Medical options are available to reduce your future cancer risk or find cancer early.
What it means for your family
Family members who have genetic testing should test for the same genetic change you have.
Negative test result
The test did not find a genetic change that increases your risk for cancer.
What it means for you
The test did not find a genetic change that caused your cancer. Further testing may be available.
What it means for your family
Genetic testing in your family members is unlikely to be helpful unless another family member has had colorectal cancer or has a known genetic change.
Negative genetic test result, but abnormal tumor screening
Although the test did not find a genetic change, you could still have Lynch syndrome.
What it means for you
Medical options are available to reduce your future cancer risk or find cancer early.
What it means for your family
Genetic testing in your family members is unlikely to be helpful unless another family member has had colorectal cancer or has a known genetic change.
Variant of uncertain significance (VUS)
The test found a genetic change in one of the genes associated with Lynch syndrome, but whether that specific genetic change causes cancer is unknown.
What is means for you
In the future, more information may be available about whether the genetic change you have causes cancer. Further testing may be available.
What it means for your family
Family members typically should not be tested for a VUS until researchers determine whether or not it causes cancer.
If you have not had colorectal cancer
If you have a family health history of colorectal or other Lynch syndrome-related cancers but have not had colorectal or another Lynch syndrome-related cancer, here's what the test results mean for you and your family:
Positive test result
You have a genetic change known to cause hereditary colorectal cancer.
What it means for you
Medical options are available to reduce your future cancer risk or find cancer early.
What it means for your family
Family members who have genetic testing should test for the same genetic change you have.
Negative test result
The test did not find a genetic change that increases your risk for cancer.
What it means for you
Results are considered uninformative because either you did not inherit the genetic change in your family, or the test did not include it. You are still considered at increased risk for cancers that run in your family. Medical options are available for prevention.
What it means for your family
Genetic testing in your family members should ideally start with someone who has had colorectal cancer or another Lynch syndrome related cancer.
Negative test result and tested for genetic change that runs in your family
You do not have the genetic change that runs in your family.
What it means for you
You are not at higher risk than the average person for colorectal cancer. You cannot pass the genetic change on to your children.
What it means for your family
Your children cannot inherit the genetic change that runs in your family and do not need to be tested. Other family members could still inherit the genetic change and should be tested for the genetic change that runs in your family.
Variant of uncertain significance (VUS)
The test found a genetic change in one of the genes associated with Lynch syndrome, but whether that specific genetic change causes cancer is unknown.
What it means for you
You are still considered at increased risk for cancers that run in your family. Medical options are available for prevention.
What it means for your family
Family members typically should not be tested for a VUS until researchers determine whether or not it causes cancer.
Having a family health history of colorectal, uterine, and other cancers does not mean that you have Lynch syndrome. Most colorectal cancer is not caused by inherited genetic changes, so Lynch syndrome testing will not benefit most people with a family health history of colorectal cancer who have not had cancer themselves. Genetic testing will not identify the cause for some hereditary colorectal, uterine, and other cancers, because the genes affected in these cancers are not yet known.