What is Lynch Syndrome?

In people with Lynch syndrome, a change or mutation in certain genes may allow the formation of small growths of tissue called polyps. Polyps in the colon are usually benign (noncancerous). However, the type of polyp most often seen in Lynch syndrome, called an adenoma, is precancerous and has the potential to develop into cancer. In Lynch syndrome, these polyps can become cancerous more quickly than expected.

In the United States, about 160,000 new cases of colon cancer are diagnosed each year. Doctors estimate that 3 out of every 100 colon cancers are caused by Lynch syndrome.

Inheriting a gene mutation ultimately puts you at higher risk. If one of your parents carries a Lynch syndrome gene mutation, you may carry this mutation also. The Lynch syndrome gene mutation can lead to an 82% risk of developing colon cancer by age 70. For women, the gene can also lead to a 71% risk of developing endometrial cancer by age 70. Risks for other cancers, such as ovarian and stomach, are increased as well. The risk of colon cancer is dependent on which gene you carry a mutation in.

If you or a family member has a history of cancer, you should talk to your doctor about assessing your families’ risk for Lynch syndrome. Tests are available to help identify the genes, which indicate the presence of Lynch syndrome.

Lynch syndrome is the most common cause of hereditary colon cancer.

About three to five percent of colon or rectal cancers (colorectal cancers) are believed to be caused by mutations in the MLH1, MSH2, MSH6, PMS2 or EPCAM genes. When someone carries a harmful mutation in any of these genes, they have a condition called Lynch syndrome, which is also called Hereditary Non-polyposis Colorectal Cancer (HNPCC) 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, rarely, urinary tract, renal/pelvic, biliary tract, small bowel, pancreatic, and brain cancers

Some people with Lynch syndrome may also develop sebaceous adenomas, which are noncancerous tumors of an oil-producing gland in the skin.

Risk Factors for Lynch Syndrome

Knowing your risk for Lynch syndrome 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 a personal history of:

  • Colorectal or endometrial cancer before age 50
  • Abnormal tumor test results (colorectal/endometrial)
  • Two or more Lynch syndrome cancers** at any age
  • A Lynch syndrome cancer** with one or more relatives also with a Lynch syndrome cancer**
  • A previously identified Lynch syndrome or MAP syndrome mutation in the family

You have any of the following family histories:

  • A first or second degree relative with colorectal or endometrial cancer before the age of 50
  • Two or more relatives with a Lynch syndrome cancer** before the age of 50
  • Three or more relatives with a Lynch syndrome cancer** at any age
  • A previously identified Lynch syndrome or MAP syndrome mutation in the family

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