Lynch Syndrome

Lynch syndrome is a genetic condition that increases the odds of a person developing several cancers and developing them earlier than normal, often colorectal cancer, endometrial cancer and ovarian cancer. Lynch syndrome can also increase the chance of developing biliary cancer, brain cancer, pancreatic cancer, stomach cancer and cancers of the urinary tract.

Lynch syndrome is also called hereditary non-polyposis colorectal cancer syndrome. It is caused by a mutation in any one of five genes: MLH1, MSH2, MSH6, PMS2, and EPCAM.

Genes are the set of instructions that tell cells what to do. A gene mutation is a change in a gene’s DNA that causes that gene to stop working.

The genes that cause Lynch syndrome all make proteins that help repair damaged DNA. The mutated genes are not able to make these proteins. This lets some cells with damaged DNA turn into cancer cells.

People with a personal and/or family history of colorectal cancer or endometrial cancer may meet the criteria to test for Lynch syndrome.

Genetic testing may be especially important for people recently diagnosed with one of these cancers. They may need different treatments than those without a mutation. In addition, the specific features of a patient’s tumor may indicate it is caused by Lynch syndrome. These patients should be tested, as well.

Talk to your doctor about whether you qualify for genetic counseling and testing.

Lynch syndrome: understanding your risk

The risk of developing certain cancers changes depending on which Lynch syndrome gene mutation a person has.

Lifetime risks without Lynch syndrome

Colorectal cancer, endometrial cancer and ovarian cancer are the three diseases most impacted by Lynch syndrome. The chances of developing these cancers for someone without Lynch syndrome are:

• Colorectal cancer: 4.1%
• Endometrial cancer: 3.1%
• Ovarian cancer: 1.1%

MLH1 mutation lifetime risks

• Colorectal cancer: 46%-61%
• Endometrial cancer: 34%-54%
• Ovarian Cancer: 4% to 20%

MSH2 and EPCAM mutations lifetime risks

• Colorectal cancer: 33%-52%
• Endometrial cancer: 21%-57%
• Ovarian cancer: 8%-38%

MSH6 mutation lifetime risks

• Colorectal cancer: 10%-44%
• Endometrial Cancer: 16%-49%
• Ovarian cancer: 1% to 13%

PMS2 mutation lifetime risks

• Colorectal cancer: 8.7%-20%
• Endometrial cancer: 13%-26%
• Ovarian cancer: 1.3%-3%

Genetic Testing for Lynch syndrome: Family History and Risk Assessment

In most cases, Lynch syndrome is passed down from parent to child.

If a person has Lynch syndrome, their children have a 50% chance of inheriting the condition. Their parents and siblings also have a 50% chance of having the syndrome. Blood relatives of people with a mutation, including aunts, uncles and cousins, may also carry the mutated gene.

Partners of people diagnosed with Lynch syndrome should consider testing, too. The children of two people with the condition may inherit mutated genes from both parents, putting them at very high risk for of developing cancer at a young age. This is a very rare condition, though.

Genetic testing for Lynch syndrome

When a person is diagnosed with Lynch syndrome, their parents, siblings and children should meet with a genetic counselor to discuss genetic testing. Testing typically requires a blood or saliva sample to test for the inherited mutation.

Testing an individual’s parents can reveal which side of the family the mutation was inherited from. Blood relatives on that side of the family, including aunts, uncles and cousins, should also consider genetic counseling.

If parents are unavailable for testing, both sides of the family should consider genetic counseling. During a genetic counseling appointment, the counselor will review personal and family medical history and discuss genetic testing options.

If you pursue genetic testing, a genetic counselor will explain your test results to you. If you are diagnosed with Lynch syndrome, your genetic counselor and health care providers will talk to you about cancer prevention and screening options.

Learn more about genetic testing.

Lynch syndrome and colorectal cancer

Depending on the exact gene mutation, colorectal cancer screening for people with Lynch syndrome should start as young as age 20 and could include a yearly colonoscopy. Learn more about colorectal cancer screening.

Lynch syndrome and gynecologic cancers

Women with Lynch syndrome should get screening for endometrial cancer starting as young as age 30. This screening should include a pelvic exam, endometrial biopsy and vaginal ultrasound every two to three years. They should also speak to their doctors about regular ovarian cancer screening. Learn more about endometrial cancer screening and ovarian cancer screening.

In addition to screening, guidelines from the National Comprehensive Cancer Network recommend some women with Lynch syndrome get a hysterectomy to prevent cancer from developing. This is only a guideline, and women can discuss surgery timing with their doctors.

Since a hysterectomy prevents women from bearing children, many women with Lynch syndrome can delay surgery until after they have given birth. Women should talk with their care team about their goals around family planning. If they choose to delay surgery, their care team can develop a plan for more frequent cancer screenings.

Additional cancer screenings

Since Lynch syndrome can increase the risk of developing several additional cancers, your care team may recommend more screening exams and physical exams to check for these diseases.