Colorectal Cancer: Genetic Testing for Inherited Mutations
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People with colorectal cancer should ask about genetic testing
Up to 10% of people diagnosed with colorectal cancer have an that caused their cancer. There are national guidelines that outline who should consider genetic counseling and testing for an linked to cancer. Speak with an expert about genetic testing for the following situations.
Experts recommend tumor testing all colorectal cancers to look for biomarkers known as "" () or microsatellite instability-High () at the time of diagnosis. These two related abnormalities are commonly found in the cancers of people with .
- People with dMMR/MSI-High cancers are recommended to have genetic counseling and testing for .
- dMMR/MSI-High cancers can occur in people who do not have . Not all people with cancers will test positive for a mutation.
- People with inherited mutations who develop colorectal cancer may have cancers that do not have these biomarkers.
- People with cancers that are not may still benefit from genetic counseling and testing.
- Cancers with these biomarkers tend to respond well to treatment with a certain type of treatment known as .
Genetic counseling and testing for an is also recommended for people diagnosed with colorectal cancer who have any of the following personal history of polyps:
- 10 or more of the adenomatous type
- 2 or more of the hamartomatous type
- 5 or more of the serrated type close to the rectum
Genetic counseling and testing for an is also recommended for people diagnosed with colorectal cancer who have any of the following:
- a blood relative with a known in a colorectal cancer gene.
- diagnosed before age 50.
- diagnosed with another related cancer including endometrial, ovarian, pancreatic, stomach or other Lynch syndrome-related cancer.
- a close relative with a Lynch syndrome-related cancer diagnosed under age 50.
- two or more relatives with a Lynch syndrome-related cancer diagnosed at any age.
Other colorectal cancer survivors who may benefit from genetic counseling and testing
Genetic counseling and testing is also recommended for anyone with the following family history of colorectal cancer:
- one or more 1st-degree relatives who has been diagnosed with colorectal cancer before age 50.
- one or more 1st-degree relatives wo have been diagnosed with colorectal cancer and a second cancer related to (e.g., colon cancer).
- two or more 1st- or 2nd- degree relatives who have been diagnosed with a cancer related to with at least one of the cancers diagnosed before age 50.
- three or more 1st- or 2nd- degree relatives who have been diagnosed with a cancer related to at any age.
Relatives of people with colorectal cancer may also benefit from testing.
Genetic counseling and testing is also recommended for anyone with the following family history of colorectal cancer:
- one or more 1st-degree relatives who has been diagnosed with colorectal cancer before age 50.
- one or more 1st-degree relatives wo have been diagnosed with colorectal cancer and a second cancer related to (e.g., colon cancer).
- two or more 1st- or 2nd- degree relatives who have been diagnosed with a cancer related to with at least one of the cancers diagnosed before age 50.
- three or more 1st- or 2nd- degree relatives who have been diagnosed with a cancer related to at any age.
Genes linked to colorectal cancer
Mutations in the following genes have been linked to increased risk for colorectal cancer.
Syndrome (if applicable) |
Genes |
Notes |
Lynch syndrome |
Lynch syndrome is the most common inherited syndrome linked to colorectal cancer. People with Lynch syndrome who develop colorectal cancer are most likely to have tumors that are MSI-H or dMMR. People with Lynch syndrome have an increased risk for other types of cancers, too. |
|
Familial Adenomatous Polyposis (FAP) and Atypical Familial Adenomatous Polyposis (AFAP) |
People with FAP mutation may develop 100s of polyps and they may be diagnosed with colorectal cancer at a young age. People with FAP have an increased risk for other types of cancers. |
|
MUTYH Associated Polyposis (FMAP) |
People must have mutations in both copies of the MUTYH gene in order to develop this syndrome. People with MAP have an increased risk for other gastrointestinal tract cancers, too. |
|
PTEN Hamartoma Tumor syndrome |
People with PTEN Hamartoma Tumor syndrome have an increased risk for other types of cancers. |
|
Li-Fraumeni syndrome |
People with Li-Fraumeni syndrome have an increased risk for other types of cancer. |
|
Peutz-Jeghers syndrome |
Peutz-Jegher syndrome have an increased risk for other types of cancer. |
|
Multiple Endocrine Neoplasia 1 syndrome (MEN1) |
MEN1 |
MEN1 is linked to an increased risk for a type of tumor known as a neuroendocrine tumor. These tumors can occur in the gastrointestinal tract, including the colon. |
Other rare genes linked to colorectal cancer |
MSH3, NTHL1, AXIN2, GREM1, BMPR1A, SMAD4, POLE, POLD1 |