What is Lynch syndrome?

This page was reviewed under our medical and editorial policy by

Eric Fowler, MS, LCGC, Manager, Clinical Genetics, Western Region & Licensed Certified Genetic Counselor

This page was reviewed on July 14, 2021.

Lynch syndrome is an inherited condition, meaning that it’s caused by altered genes passed down from one's parents. Having Lynch syndrome increases the risk of developing many types of cancer at earlier-than-average ages.

Anyone with Lynch syndrome faces an especially high risk of colorectal cancer—about 4,000 cases of colorectal cancer are caused by Lynch syndrome every year, according to the U.S. Centers for Disease Control and Prevention (CDC). The condition is also called hereditary non-polyposis colorectal cancer (HNPCC).

Women with the condition also have an increased risk of endometrial cancer (cancer of the uterus). Lynch syndrome causes about 1,800 cases of endometrial cancer every year, according to the CDC. Other cancers that people with Lynch syndrome are more likely to develop include:

Mutations and family history

Lynch syndrome is common compared with other inherited cancer syndromes—it’s estimated that about one in 300 people have the condition, according to the American Society of Clinical Oncology (ASCO).

People with Lynch syndrome have inherited changes (mutations) in particular genes, such as MLH1, MSH2, MSH6, PMS2 and EPCAM. When mutations are present in these genes, they repair acquired changes in the DNA, making it easier for cancer to develop.  

Those with a strong family history of colorectal cancer or other Lynch syndrome-related conditions should inform their doctor. The children and siblings of someone with Lynch syndrome have a 1 in 2, or a 50 percent, chance of also having the condition, according to the American Cancer Society. If Lynch syndrome is suspected because of family history, doctors may recommend genetic counseling and genetic testing.

If genetic tests reveal a mutation associated with Lynch syndrome, recommendations may include:

  • Colonoscopies every one to two years, generally starting between the ages of 20 and 30
  • Women have a discussion with their doctor about:
    • The benefits and limitations of screening for endometrial and ovarian cancer
    • Risk-reducing surgeries, which may include the removal of the uterus, ovaries and fallopian tubes
  • Screening for stomach, urinary tract and possibly other cancers, depending on family history

Lynch syndrome and risks of developing cancer

Certain gene mutations associated with Lynch syndrome carry higher risks of cancer than others. Below find the estimated lifetime cancer risks for people with Lynch syndrome, according to ASCO.

  • Colorectal cancer: 20 percent to 80 percent
  • Liver/bile duct cancer: 1 percent to 4 percent
  • Stomach cancer: 1 percent to 13 percent
  • Small bowel cancer: 1 percent to 6 percent
  • Urinary tract cancer: 1 percent to 18 percent
  • Brain cancer: 1 percent to 3 percent
  • Pancreatic cancer: 1 percent to 6 percent
  • Endometrial cancer: 15 percent to 60 percent
  • Ovarian cancer: 1 percent to 38 percent

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