Hereditary colon cancer risk and genetic testing

Take care of your health by understanding your genetic risk of hereditary colon cancer. Genetic testing insights can help you and your healthcare provider take immediate steps toward an effective medical management plan.

Fast facts on colon cancer

4.1% of U.S. men and women will be diagnosed with colon cancer during their lifetime1

Hereditary colon cancer risk can be as high as >99% for people with specific genetic mutations

Knowing your hereditary colon cancer risk helps you and your healthcare provider take preventive action that could potentially save your life

Is colon cancer hereditary?

Colon or rectal cancers can be caused by hereditary mutations passed down through generations of family members. Two syndromes are often the cause of hereditary colon cancer: Lynch syndrome and Polyposis.

What is Lynch syndrome?

Also called hereditary non-polyposis colorectal cancer (HNPCC) syndrome, Lynch syndrome is an inherited condition that increases a person’s risk of developing colon cancer and other cancers. Individuals with Lynch syndrome carry a harmful mutation in the MLH1, MSH2, MSH6, PMS2 and EPCAM genes. Mutations in these genes are the cause of approximately three to five percent of hereditary colon or rectal cancers (colorectal cancers).2

Is Lynch syndrome serious?

Lynch syndrome increases one’s risk of developing many types of cancer, and people diagnosed with the condition are more likely to develop cancer before the age of 50.3 If you have been diagnosed with Lynch syndrome or have a family history of colorectal cancer, consider visiting your healthcare provider for a cancer screening.

What cancers are linked to Lynch syndrome?

People with Lynch syndrome are at higher risk of developing several different types of cancer, including:

  • Colorectal cancer
  • Endometrial (uterine) cancer
  • Ovarian cancer
  • Gastric (stomach) cancer

In addition, the risk of developing urinary tract, renal, pelvic, biliary tract, small bowel, pancreatic, and brain cancers may also be higher.

What are the signs or symptoms of Lynch syndrome?

Many people with Lynch syndrome will experience no symptoms well into adulthood, which makes genetic testing even more important for those with a family history of colorectal cancers. If symptoms do manifest, they are commonly similar to those of cancers caused by Lynch syndrome, including:4

  • Bloody stool
  • Constipation
  • Diarrhea
  • Abdominal cramps
  • Bloating
  • Vomiting
  • Fatigue

What is polyposis?

Polyposis includes several syndromes characterized by the formation of polyps (abnormal growths) on the lining of the colon or other parts of the gastrointestinal tract. Most colon polyps are benign, but some may develop into colon cancer. Approximately two percent of all colon cancer is thought to be caused by two conditions related to adenomatous polyposis, or abnormal polyp growths:5

  • Familial adenomatous polyposis (FAP)
  • MUTYH-associated polyposis (MAP)

Colon cancer risks: Familial adenomatous polyposis (FAP)

FAP is a genetic disorder that increases a person’s likelihood of developing adenomas, or precancerous colon polyps. While it’s common for people to develop a small number of colon polyps as they age, those with a hereditary syndrome like FAP will develop many, starting from a younger age. The more colon polyps a person develops, the greater the likelihood that one will become cancerous.
FAP (or “classic” FAP) is characterized by the presence of 100+ adenomatous polyps in one’s colon, while “attenuated” FAP is marked by 20-100 colon polyps. FAP and attenuated FAP are caused by mutations in the adenomatous polyposis coli (APC) gene.6

Colon cancer risks: MUTYH-associated polyposis (MAP)

MAP is caused by mutations in the mutY homolog (MUTYH) gene, which plays an important role in DNA repair. Individuals with MAP have mutations in both copies of their MUTYH gene, one from each parent, and they often have no family history of colon cancer or polyps in their parents (although siblings may be affected).
MAP can cause polyps to develop in the colon and rectum. As with FAP, these polyps aren’t necessarily cancerous, but some may turn into cancer. Having MAP significantly increases your risk of developing colorectal cancer, so it’s important to talk to your healthcare provider about regular cancer screenings and genetic testing.7

What percent of colon cancer cases are hereditary?

Approximately 5% of people who develop colon cancer have inherited genetic mutations (meaning they are passed down from family) that can cause various syndromes, including Lynch syndrome, familial adenomatous polyposis (FAP), and MUTYH-associated polyposis (MAP), which can lead to cancer.8

From which side of the family is colon cancer inherited?

The hereditary mutations known to be associated with Lynch syndrome, familial adenomatous polyposis (FAP), and MUTYH-associated polyposis (MAP), all of which can cause colon or rectal cancers, can be inherited from either side of the family.8

What are the chances of getting colon cancer if you have a family history of colon cancer?

Exact likelihoods are unknown, but a history of colon cancer in a first-degree relative (meaning a parent, sibling, or child) does increase your risk of developing colon cancer. Of those who do develop colon cancer, as many as 1 in 3 have a family history of the disease.8

What is the survival rate for hereditary colon cancer?

For people with hereditary non-polyposis colorectal cancer (HNPCC) syndrome, an inherited condition also known as Lynch syndrome, the survival rate at five years after diagnosis is approximately 60%. At 10 years after diagnosis, the survival rate of those with Lynch syndrome is between 70% and 80%.9

When should you get a cancer screening if you have a family history of colon cancer?

For people who have a first-degree relative with colon cancer or adenomatous polyps, a colonoscopy is recommended starting at age 40, then every five years thereafter. Genetic testing should also be considered to better understand your cancer risk factors.10

Additional hereditary risks for colon cancer
Other gene mutations and syndromes can also contribute to colon cancer risk. Learn more about genes most commonly associated with colon cancer risk and their related syndromes.

Who should get tested for hereditary colon cancer?

Knowing your risk for Lynch syndrome or polyposis syndromes can help you and your healthcare professional make better, more informed decisions about your health, before the onset of cancer or before a second cancer has had a chance to develop. Genetic testing for hereditary colon cancer should be considered if you have personal history of:*

  • Colorectal cancer at any age
  • Endometrial cancer before age 65
  • Abnormal tumor test results (colorectal/endometrial)
  • Two or more Lynch syndrome-associated cancers** at any age
  • A Lynch syndrome-associated cancer** with one or more relatives also with a Lynch syndrome-associated cancer**
  • You have multiple colorectal adenomas (usually 10 or more cumulative adenomas in your lifetime)

Genetic testing should also be considered if you have family history of:

  • A close*** relative with colorectal or endometrial cancer before age 50
  • Two or more relatives with a Lynch syndrome-associated cancer** before the age of 50
  • Three or more relatives with a Lynch syndrome-associated cancer** at any age
  • A previously identified Lynch syndrome or polyposis syndrome mutation in the family

*Assessment criteria are based on medical society guidelines.

**Lynch syndrome-associated cancers include colon, endometrial (uterine), gastric, ovarian, urinary tract, renal pelvic, biliary tract, small bowel, pancreatic, brain and sebaceous adenomas.

***Close refers to first- or second-degree relatives. First-degree relatives include parents, siblings and children. Second-degree relatives include grandparents, aunts/uncles and nieces/nephews.

How do I get tested for hereditary colon cancer?

MyRisk® Hereditary Cancer Test

The MyRisk test gives you a clearer understanding of your individual risk for 11 different types of hereditary cancers, including colon cancer. The test can determine whether you are a carrier of gene mutations associated with Lynch syndrome or polyposis syndromes, which are known to cause hereditary colon cancer. MyRisk results can give you and your healthcare provider the insights needed to help create an effective medical management plan.

Take the next step with hereditary cancer testing.

What will genetic testing results tell me?

The MyRisk test will confirm if Lynch syndrome or polyposis gene mutations are present. If they are, the medical management options below may help reduce cancer risk or detect cancer at an earlier, more treatable stage.

If a Lynch syndrome mutation is present, you and your medical provider may want to consider:

  • Increased surveillance for colon, endometrial (uterine) and ovarian cancer, such as starting cancer screening at an earlier age or being screened more frequently
  • Risk-reducing medications
  • Surgical management

If polyposis syndrome mutations are present, you and your medical provider may want to consider:

  • Increased surveillance and other interventions specifically intended for individuals with APC or MUTYH gene mutations

Your test results can also help your family members learn and understand more about inherited cancer risk and how it may affect them.

†Any discussion of medical management options is for general informational purposes only and does not constitute a recommendation. While genetic testing and medical society guidelines provide important and useful information, all medical management decisions should be made based on consultation between each patient and their healthcare professional.

Is genetic testing still useful if I’ve already been diagnosed?

If you have already been diagnosed with colon cancer, there are genetic tests to help guide you and your healthcare provider in creating an optimal medical management and treatment plan for improved outcomes.

Take the next step

Learn your risk for hereditary colon cancer

References:

  1. National Cancer Institute. Cancer stat facts: Colorectal cancer. Surveillance, Epidemiology and End Results Program. https://seer.cancer.gov/statfacts/html/colorect.html. Accessed September 27, 2022.
  2. Giardiello FM, et al. (2014) Guidelines on Genetic Evaluation and Management of Lynch Syndrome: A Consensus Statement by the US Multi-Society Task Force on Colorectal Cancer. Am J Gastroenterol. 2014 109:1159-79.
  3. American Cancer Society. Lynch Syndrome. https://www.cancer.org/cancer/risk-prevention/genetics/family-cancer-syndromes/lynch-syndrome.html. Accessed October 25, 2024.
  4. Johns Hopkins Medicine. Lynch Syndrome. https://www.hopkinsmedicine.org/health/conditions-and-diseases/lynch-syndrome.
  5. Burt R, Neklason DW (2005). Genetic testing for inherited colon cancer. Gastroenterology 2005 May;128(6):1696-716.
  6. Cleveland Clinic. Familiar Adenomatous Polyposis (FAP). https://my.clevelandclinic.org/health/diseases/16993-familial-adenomatous-polyposis-fap.
  7. Cleveland Clinic. MUTYH-Associated Polyposis (MAP). https://my.clevelandclinic.org/health/diseases/17254-mutyh-associated-polyposis-map.
  8. American Cancer Society. Colorectal Cancer Risk Factors. https://www.cancer.org/cancer/types/colon-rectal-cancer/causes-risks-prevention/risk-factors.html.
  9. Cleveland Clinic. Hereditary Nonpolyposis Colorectal Cancer (HNPCC). https://my.clevelandclinic.org/health/diseases/17097-hereditary-non-polyposis-colorectal-cancer-hnpcc.
  10. American Society of Colon & Rectal Surgeons. Colorectal Cancer Screening and Surveillance: Clinical Guideline and Rationale. https://fascrs.org/healthcare-providers/education/clinical-practice-guidelines/colorectal-cancer-screening-and-surveillance-clini.