What is Lynch Syndrome?

Lynch syndrome, also known as hereditary non-polyposis colorectal cancer (HNPCC) is a rare genetic condition that runs in families and increases the risk of developing bowel cancer and other cancers. It is the most common cause of hereditary bowel cancers and accounts for between 2-5% of all bowel cancers. Between 70-90 percent of people with Lynch syndrome will develop bowel cancer and the average age of developing bowel cancer is much lower (below 50).

Other cancers that may develop if you have Lynch syndrome

As well as an increased risk of bowel cancer, people with Lynch syndrome are also at a greater risk of a number of other cancers including:

• Womb
• Stomach
• Ovarian
• Pancreatic
• Prostate
• Urinary tract
• Liver
• Kidney
• Bile duct

What causes Lynch syndrome?

Lynch syndrome is caused by a mutation in one or more of the following genes. If a person inherits an altered (mutated) copy of the gene, they are at higher risk of developing cancer.

• MLH1
• MSH2
• MSH6
• PMS2
• EPCAM

GeneHealth UK is able to offer genetic testing for all of these genes and others related to bowel cancer.

Indications that there may be Lynch syndrome in a family

Doctors use something called the revised Bethesda criteria to identify who should be offered testing for Lynch syndrome. Individuals meeting any of the following criteria should be offered tumour testing for Lynch syndrome:

1. Colorectal cancer diagnosed before age 50 years of age.
2. Colorectal cancer with a rare pathology^* diagnosed before age 60 years of age.
3. Colorectal cancer and another Lynch syndrome associated tumour ^**
4. Colorectal cancer and 2+ relatives with colorectal cancer at any age
5. Colorectal cancer and 1 relative diagnosed with colorectal cancer before age 50

^* tumor infiltrating lymphocytes, Crohn’s-like lymphocytic reaction, mucinous/signet-ring differentiation, or medullary growth pattern.
^** bowel, small bowel, womb, stomach, ovarian, pancreas, urinary tract, biliary tract, brain tumors, sebaceous gland adenomas and keratoacanthomas.

Reducing risk and early detection

Diagnosing Lynch syndrome early is important in improving outcomes as it allows you to be screened from an earlier age and, in some cases, offered surgery or medication to help reduce the risk of developing cancers associated with this condition. As with all cancers, early detection saves lives.