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Lynch syndrome

4-minute read

Lynch syndrome is a genetic condition that puts a person at higher risk of developing certain types of cancer, including bowel cancer.

If you have Lynch syndrome, formerly known as hereditary non-polyposis colorectal cancer (HNPCC), you will need regular monitoring with colonoscopies, as well as other tests. Some people with Lynch syndrome may be advised to have preventative surgery.

What is Lynch syndrome?

Lynch syndrome is caused by a mutation in a specific type of gene. It significantly increases a person's risk of developing some types of cancer, such as bowel cancer (also known as colorectal cancer) and endometrial cancer (also known as uterine cancer). But having Lynch syndrome does not mean you will develop cancer.

People with Lynch syndrome often develop cancers at an earlier age than the general population.

Lynch syndrome can also lead to an increased risk of:

Who is at risk of Lynch syndrome?

People who have one parent with Lynch syndrome have a 1 in 2 chance of inheriting it. If you have been diagnosed with Lynch syndrome, any child you have will also have a 1 in 2 chance of inheriting the condition.

Lynch syndrome can't 'skip a generation', so if your children do not inherit Lynch syndrome, they can't pass it on to your grandchildren.

But not all people with Lynch syndrome have a family history of the condition. You can be the first one in your family to be diagnosed with it.

You may consider genetic counselling or testing if a close family member has been diagnosed with Lynch syndrome.

How is Lynch syndrome diagnosed?

Lynch syndrome is usually diagnosed with genetic tests (blood tests). Some people might choose to be tested for Lynch syndrome after a member of their family is diagnosed with the condition, even if they have no signs of any illness themselves.

If these factors apply to your family, your doctor may suspect you have Lynch syndrome, and recommend testing:

  • 3 or more members of the family have a cancer associated with Lynch syndrome
  • 1 relative is a first-degree relative (parent, brother or sister, or child) of the other 2 relatives
  • 2 consecutive generations or more are affected
  • at least 1 member of the family developed their cancer before the age of 50

Other people may be tested for Lynch syndrome because they have developed one of the relevant cancers at a young age, or because there is a lot of cancer in their family.

If you are being investigated for Lynch syndrome, the doctor will examine you, take a family history, assess your risk and decide whether to refer you for genetic testing.

You should be offered genetic counselling with a genetic specialist before and after the tests.

If you are diagnosed with Lynch syndrome

You may be advised to have a colonoscopy every year, so doctors can pick up any signs of polyps and bowel cancer early.

Your doctors might recommend taking aspirin daily from when you have your first colonoscopy (usually at age 25) to reduce the risk of bowel cancer.

Managing cancer risk with lifestyle

If you know you have Lynch syndrome, you might be able to reduce your risk of developing cancer by:

  • not smoking
  • maintaining a healthy weight
  • reducing alcohol consumption

There is also some evidence that:

  • women with Lynch syndrome who use hormonal contraceptives (for more than 1 year) may have a lower risk of developing cancer than those who don't
  • women with Lynch syndrome who have children may have a lower risk of developing cancer than women who don't
  • multivitamins and calcium supplements might reduce a person's risk of developing cancer if they have Lynch syndrome

Risk-reducing surgery

If you have Lynch syndrome and colon cancer, your doctor might recommend removing a larger than normal section of the colon to reduce the risk of secondary cancer. Discuss the pros and cons of this with your doctors.

Women with Lynch syndrome might be advised to consider a hysterectomy and removal of their ovaries once they've finished having children. This is to prevent endometrial or ovarian cancer. Discuss the pros and cons of this with your gynaecological oncologist (women's cancer specialist).

Where to get more information

Last reviewed: March 2019

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