What Is Lynch Syndrome? (QnA)

Q. What Is Lynch Syndrome?

A. Lynch syndrome, also known as hereditary non-polyposis colorectal cancer (HNPCC), is a type of inherited cancer syndrome associated with a genetic predisposition to different cancer types.

Q. What Cancers Are Caused By Lynch Syndrome?

A. Variations in the MLH1, MSH2, MSH6, PMS2, or EPCAM gene increase the risk of developing Lynch syndrome.

Although mutations in these genes predispose individuals to cancer, not all people who carry these mutations develop cancerous tumors.

Q. Frequency Of Occurrence Of Lynch Syndrome?

A. Approximately 3 to 5 percent of these cancers are caused by Lynch syndrome.

Q. Does Lynch Syndrome Runs In Family And What Does It Mean?

A. Lynch syndrome cancer risk is inherited in an autosomal dominant pattern, which means one inherited copy of the altered gene in each cell is sufficient to increase cancer risk.

This means that if one parent carries a gene mutation for Lynch syndrome, there's a 50 percent chance that mutation will be passed on to each child. 

Q. What Is The Life Expectancy Of Someone With Lynch Syndrome?

A. Lynch syndrome lifetime risk of cancer

  • MLH1/MSH2 , 14 to 54%; Average age at diagnosis: 48 to 62.
  • MSH6, 17 to 71%; Average age at diagnosis: 54 to 57. 
  • PMS2, 15%; Average age at diagnosis: 49.

Q. What Are The Diagnostic Criteria Followed?

A. Diagnostic criteria for Lynch syndrome (hereditary non-polyposis colorectal cancer, HNPCC):

Revised Bethesda Diagnostic criteria, (Umar A. et al., J Natl Cancer Inst. 2004;96(4):261-8)

Below are the Revised Bethesda Guidelines for testing colorectal tumors for microsatellite instability (MSI):

  1. Colorectal or uterine cancer diagnosed in a patient how is less than 50 years of age
  2. Presence of synchronous, metachronous colorectal, or other HNPCC-associated tumors,  regardless of age.
  3. Colorectal cancer with the MSI-H  histology diagnosed in a patient who is less than 60 years of age. 
  4. Colorectal cancer diagnosed in one or more first-degree relatives with an HNPCC-related tumor, with one of the cancers being diagnosed under age 50 years.
  5. Colorectal cancer diagnosed in two or more first- or second-degree relatives with HNPCC-related tumors, regardless of age.

If suspected for lynch syndrome doctor will ask the following question:

  • Family history
  • Tumor testing can reveal whether your cancer was caused by genes related to Lynch syndrome. Tumor tests include:

Immunohistochemistry (IHC) testing.

Microsatellite instability (MSI) testing. 

  • Genetic testing

Q. What Treatment Regimen Is Followed For Lynch Syndrome?

A. Colon cancer associated with Lynch syndrome is treated similarly to other types of colon cancer.

Treatments for colon cancer may include surgery, chemotherapy, and radiation therapy.


Colon cancer screening: High-definition colonoscopy creates more-detailed images, and narrowband colonoscopy uses a special light to create clearer images of the colon.

Endometrial cancer screening: Women with Lynch syndrome may consider having an endometrial biopsy every year or two.

Ovarian cancer screening: an annual ultrasound and blood test to screen for ovarian cancer.

Urinary system cancer screening: periodic screening for urinary tract cancers. Analysis of a urine sample may reveal blood or cancerous cells.

Gastrointestinal cancer screening: Endoscopy screening for stomach cancer aspirin AND LYNCH SYNDROME: Results from studies suggest that taking a daily aspirin may reduce the risk of several cancers related to Lynch syndrome.