An Overview of Lynch Syndrome

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Lynch syndrome is a hereditary syndrome linked to a higher risk of certain cancers, particularly colorectal cancer (cancer that starts in the colon or rectum), and endometrial (uterine) cancer. It is also linked to a higher risk of these cancers before the age of 50.

At least one in every 500 American adults have Lynch syndrome, but not everyone who has the syndrome develops cancer. Lynch syndrome is thought to cause about 3% of all colorectal cancers.

Other cancers associated with Lynch syndrome include gastric (stomach) cancer, ovarian, pancreatic, prostate, urinary tract, kidney, and brain cancer.

This article takes a closer look at what Lynch syndrome is and the genetic causes underlying it. It also covers how Lynch syndrome is diagnosed, and the steps people with Lynch syndrome can take to lower their cancer risk.

Doctors explain test results to patient
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Lynch syndrome has no visible symptoms. It's not a disease or a condition—it's a trait that someone carries in their genes. If a person with Lynch syndrome never develops cancer, they may never be physically affected by Lynch syndrome itself.

There is, however, a set of criteria that healthcare providers use to help them decide whether someone should be tested for Lynch syndrome. A person is more likely to have Lynch syndrome if one or more of the following criteria are present:

  • They have had colorectal or uterine cancer before the age of 50.
  • More than one parent, sibling, or child in their family developed colorectal cancer before the age of 50.
  • More than two first-degree or second-degree relatives (including aunts, uncles, grandparents, grandchildren, nephews, and nieces) developed colorectal cancer.
  • At least two generations were affected by cancer due to Lynch syndrome.


Lynch syndrome is also known as hereditary non-polyposis colorectal cancer (HNPCC). Non-polyposis means that colorectal cancer can occur when there are a small number of polyps present—or none at all.

A polyp is a growth that forms—in the case of colorectal cancer—on the lining of the colon or rectum. Polyps are fairly common in American adults. They are usually harmless and benign (noncancerous), but some polyps can become cancerous. This is far more likely to happen in people with Lynch syndrome.

Lynch syndrome is caused by mutations in the genes MLHL, MSH2, MSH6, PMS2, and EPCAM. These genes normally protect you from getting certain cancers. But the mutations that are responsible for Lynch syndrome prevent them from doing so.

Having the gene mutations that underlie Lynch syndrome places someone at an increased risk for developing certain cancers. Not everyone with Lynch syndrome develops cancer, though.

Colorectal cancer can be caused by several other factors, not just Lynch syndrome. Being mindful of these causes and their potential to impact your health is the best course of action for those with Lynch syndrome.

Whether or not a person has Lynch syndrome, a healthy lifestyle is a key part of cancer prevention. This will provide an individual with the best chance of lowering their cancer risk despite the presence of a mutation.


According to the American Society of Clinical Oncology, all people diagnosed with colorectal cancer should be tested for Lynch syndrome, not just those who meet the criteria for Lynch syndrome testing. Those who have been diagnosed with uterine cancer should be considered for Lynch syndrome testing as well.

Tests used to diagnose or screen for Lynch syndrome include:

  • Blood test: The most definitive way to diagnose Lynch syndrome is through a blood test, which can identify the presence of a gene mutation.
  • Microsatellite instability (MSI) testing: This test can determine whether a tumor has high or low microsatellite instability—areas of repeated, unstable DNA activity that are present due to specific gene mutations. Someone with a high MSI is likely to have Lynch syndrome, but not always. If a high MSI is detected, further genetic blood testing should be ordered to confirm a Lynch syndrome diagnosis.
  • Immunohistochemistry test (IHC): This analysis will indicate whether certain proteins inside of a tumor are missing, which often points toward the presence of Lynch syndrome.

It is recommended that genetic testing is completed after both the MSI and the IHC tests are done. Genetic testing will verify the results from these tests, which may or may not indicate Lynch syndrome.

When to Screen

Screening is recommended for people who have a family or personal medical history that could be consistent with Lynch syndrome. The revised Amersterdam criteria and the revised Bethesda criteria are often used as guides for screening.

Amsterdam criteria (must have all four of the following):

  • At least three relatives with cancer on the narrow HNPCC spectrum, one of whom is related to the other two in the first degree
  • At least one relative who had cancer was diagnosed before the age of 50
  • At least two successive generations are involved
  • Exclusion of familial polyposis

Bethesda criteria (must have at least one of the following):

  • Colorectal cancer (CRC) diagnosed before the age of 50
  • Microsatellite instability and/or loss of MMR protein expression on IHC before age 60
  • Two synchronous or metachronous cancers belonging to the broad HNPCC spectrum regardless of age
  • CRC and two or more first or second-degree relatives with cancer of the broad HNPCC spectrum regardless of age
  • CRC and a first-degree relative with HNPCC broad-spectrum cancer diagnosed before 50 years


There is no way to change your genes or any gene mutations you are born with. Therefore, there is also no cure for Lynch syndrome.

If a person with Lynch syndrome develops cancer, their treatment will be cancer-specific. That may include radiation, chemotherapy, surgery, immunotherapy, and other methods. Treatments vary depending on how severe the cancer is and the body parts that are affected.


While Lynch syndrome itself cannot be treated or prevented, you can take extra steps to lower your risk of cancer, whether you have been diagnosed with Lynch syndrome or not.

There are prevention methods specific to colorectal cancer and uterine cancer. There are also general prevention and screening methods that can assist in early diagnosis and maximize the chances for recovery and remission.

Once an individual with Lynch syndrome reaches 20 years of age, regular cancer screening options are recommended.

Cancer screening includes:

  • Receiving yearly colonoscopies
  • Endoscopies to the upper gastrointestinal tract every three to five years
  • Skin self-checks and regular skin examinations
  • Yearly pelvic examinations with ultrasounds and biopsies as needed

Some professionals recommend a daily dose of aspirin to specifically assist in decreasing a person’s risk for colorectal cancer. This has been proven as somewhat effective. But not every healthcare provider accepts it as standard practice.

Many individuals who are diligent enough to find colorectal cancer in its early stages often opt to remove portions of the colon to prevent the recurrence of cancer. Similarly, many females, particularly post-menopausal females, have a complete hysterectomy done to remove the uterus and ovaries. Doing so reduces their risk of uterine and/or ovarian cancer.

Yearly urine tests are routine parts of physical examinations. They should be done regularly to screen for cancer of the urinary tract, which some patients with Lynch syndrome have an increased risk of.

A healthy lifestyle is at the core of disease prevention, cancer included. This means refraining from recreational drugs, smoking, and excessive alcohol intake. It also means getting plenty of physical exercise, and maintaining a healthy diet.


Lynch syndrome involves inherited gene mutations that increase a person's risk of specific cancers, particularly colorectal cancer. Not everyone with Lynch syndrome develops cancer. People with a personal or family history of colorectal cancer before the age of 50 should be tested for Lynch syndrome.

The syndrome itself cannot be treated or prevented. However, living a healthy lifestyle and being screened for cancer regularly can help reduce cancer risk.

A Word From Verywell

If you find the possibility of being diagnosed with cancer is too difficult to handle, you may want to discuss options for your mental health with your healthcare provider.

Support groups, stress management, meditation, yoga, productive leisure activities, and social interaction can help you maintain a positive outlook, regardless of your health status. As always, don't hesitate to bring any questions or concerns about cancer prevention to your healthcare provider.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. Lynch syndrome.

  2. American Society of Clinical Oncology. Lynch syndrome.

  3. Stoffel E, Mangu P, Gruber S, et al. Hereditary colorectal cancer syndromes: American Society of Clinical Oncology Clinical Practice Guideline endorsement of the familial risk-colorectal cancer: European Society for Medical Oncology Clinical Practice Guidelines. J Clin Oncol. 2015 Jan;33(2):209-217. doi:10.1200/JCO.2014.58.1322

  4. Centers for Disease Control and Prevention. Microsatellite instability (MSI) screening.

  5. Onka B, Mohamed DA, Yehouenou RTT, Adeyemi B, Traore WM, Kevin Arthur MM, Jerguigue H, Latib R, Omor Y. A tumor association to be aware: endometrial cancer and colon cancer in relation to Lynch syndrome. BJR Case Rep. 2022 Jan 12;8(2):20210230. doi:10.1259/bjrcr.20210230

  6. American Cancer Society. Treating colorectal cancer.

  7. American Cancer Society. Genetic testing, screening, and prevention for people with a strong family history of colorectal cancer.

By Brittany Ferri
Brittany Ferri, MS, OTR-L, CCTP, is an occupational therapist, consultant, and author specializing in psychosocial rehab.