Some people have inherited genetic syndromes that increase their risk for colon cancer. Genetic testing looks for these inherited syndromes along with changes in DNA that are associated with a greater likelihood of developing cancer.
Colorectal cancer (CRC) is cancer that develops in your colon or rectum. The
Several factors increase the risk of CRC. One of these is having a family history of CRC. In some cases, cancer that runs in families may be due to a known genetic syndrome that increases cancer risk.
Genetic testing is available to help find out if you have gene changes that are associated with an increased risk of CRC. Keep reading below as we take a deep dive into genetic testing, who may benefit from it, and more.
Genetic testing looks for changes in your DNA that are known to be associated with an increased risk of cancer. Generally speaking, there are two ways that genetic testing may be used:
- before a person develops cancer to determine their level of risk
- following a cancer diagnosis to see if genetic changes may have contributed to the cancer
Some people that develop CRC have an inherited genetic syndrome that increases their risk for it. These syndromes are associated with specific genetic changes and include:
- Lynch syndrome
- familial adenomatous polyposis (FAP), which includes the subtypes:
- attenuated FAP
- Turcot syndrome
- Peutz-Jeghers syndrome
- MUTYH-associated polyposis
Genetic testing can look for the changes that are associated with these inherited genetic syndromes.
Further, according to the
When genetic testing is recommended, it may look for harmful changes in a single gene or in multiple genes. Multigene panels can pick up on changes in many different genes that increase the risk of CRC as well as other cancers.
Genetic testing for CRC isn’t recommended for everyone. On a general level, you may be a good candidate for genetic testing for CRC if you have:
- several close family members, such as parents, children, or siblings, who have been diagnosed with CRC
- many people on one side of your family who’ve been diagnosed with CRC
- a personal or family history of CRC coming on at a young age
- a personal or family history of an inherited genetic syndrome that increases CRC risk
- a personal or family history of multiple cancers
- a strong family history of CRC or other cancers that are associated with an inherited genetic syndrome
- more than 10 adenomatous polyps found during CRC screening
If you have concerns about your genetic risk of CRC, talk with a doctor. They can review your personal and family medical history to help determine if genetic testing is a good option for you.
As with many tests or procedures, genetic testing has both pros and cons, both of which are worth considering.
The pros, or potential benefits, of genetic testing for CRC
- A positive test result can get you started with more regular cancer screenings and empower you to take preventive steps where possible.
- A negative test result can provide you with some peace of mind.
- Genetic testing can help to inform other family members about their level of cancer risk or encourage them to get tested as well.
- A positive result when you’ve already been diagnosed with CRC may help to better inform your treatment choices or outlook.
The cons, or potential risks, of genetic testing for CRC
- A positive test result can boost stress levels or worries about developing cancer.
- A positive result can present dilemmas about whether to share that result with other family members who may be affected.
- A negative result may lead to guilt about not having harmful genetic changes that other family members have.
- Depending on the type of test used, genetic testing may not pick up on some genetic changes that could lead to cancer, so a negative result could be misleading.
- Genetic testing can be expensive.
legal protections are in place, it’s still common to have concerns about the privacy of genetic testing results.
If your doctor believes that you’re a good candidate for genetic testing, they’ll likely refer you to a genetic counselor. This is a healthcare professional that’s specially trained to assess how genetics contributes to certain health conditions.
Before your test, a genetic counselor will review your personal and family medical history. They’ll also go over the pros and cons of genetic testing, the type of test that’s recommended, and the potential impact of your results.
Genetic testing is typically done using a blood sample. However, it may also use a sample of saliva, cheek cells, or skin. This sample will be sent to a specialized lab that will run the test.
It can take
Genetic testing can be pricy. According to Breastcancer.org, genetic testing for cancer can cost anywhere between $300 to $5,000, depending on the type and extent of the testing that’s used.
As such, if your doctor recommends genetic testing, it’s important to have an open discussion about the potential costs. This not only includes the test itself, but also the genetic counseling and other services associated with it.
Many insurance providers will cover the cost of genetic testing and genetic counseling if it’s considered medically necessary. Nevertheless, always check with your insurance provider to see what’s covered before getting tested.
- high sensitivity fecal immunochemical test (FIT) or high sensitivity guaiac-based fecal occult blood test yearly
- multi-target stool DNA test every 3 years
- virtual colonoscopy or flexible sigmoidoscopy every 5 years
- colonoscopy every 10 years
However, people at a higher risk of CRC may need to begin screening before age 45. This includes people with a strong family history of CRC or inherited genetic syndromes that increase CRC risk.
When to start screening and the screening tests that are recommended can vary based on your individual situation. If you’re at a higher risk of CRC, ask your doctor about the timing and tests that are right for you.
Is there anything you can do to lower your risk of colon cancer?
While it’s not possible to completely prevent CRC, there are things that you can do to help lower your risk. Recommendations include:
- Increase your levels of physical activity.
- Manage your weight if you have overweight or obesity.
- Reduce the amount of red or processed meats in your diet.
- Boost your intake of fresh produce, whole grains, and healthy proteins.
- Add calcium-rich foods to your diet.
- Consume alcohol in moderation or not at all.
- If you smoke, try to quit smoking.
How accurate is genetic testing for colon cancer?
Genetic testing for CRC can reliably tell you if you have specific genetic changes that are associated with increased CRC risk. However, these tests cannot tell you if and when you’ll actually develop CRC.
Not everyone who has a positive result on a genetic test will get CRC. Your doctor or genetic counselor can give you a better idea of your individual level of risk.
What percentage of colon cancer is genetic?
According to the NCI,
What is the most common hereditary syndrome for colon cancer?
Lynch syndrome is the
What are the other risk factors for colon cancer?
In addition to genetic factors, the following things can increase the risk for CRC:
- older age
- a personal history of CRC or adenomatous polyps
- health conditions like:
- overweight or obesity
- a diet high in red or processed meat
- heavy alcohol use
- physical inactivity (colon cancer only)
What are the common symptoms of colon cancer?
Some of the common symptoms of CRC include:
- blood in your stool
- bleeding from your rectum
- diarrhea or constipation that lasts more than several days
- a change in stool shape, such as being narrower than is typical
- abdominal pain or cramping
- feeling like you need to have a bowel movement even though your bowel is empty
- reduced appetite
- unintended weight loss
CRC can run in families. In some situations, an inherited genetic syndrome can contribute to the development of CRC.
Genetic testing can help to detect genetic changes that can lead to CRC. However, this type of testing is typically only recommended for people with a strong family history of CRC or inherited genetic syndromes that raise CRC risk.
It’s important to be informed when deciding whether to get genetic testing for CRC. Before getting tested, talk with your doctor about the risks and benefits of testing, the cost of testing, and what different types of results could mean for you.