Inherited Genetic Disorders in Colon Cancer: Lynch Syndrome

Although most colon cancer affects people with no family history or genetic predisposition to it, a small amount of people do suffer from hereditary colon cancer. The most common of these is called Lynch Syndrome, or Hereditary (Non-Polyposis) Colon Cancer. It’s estimated that this disease is responsible for 3% of all colorectal cancers.

How do I know if I have Lynch syndrome?

Lynch Syndrome can be passed down from either parent, and if you have it, you have up to 80 percent chance of developing colon cancer in your lifetime. These are some of the factors doctors look out for:

• If you are diagnosed with colon or endometrial cancer before the age of 50
• Three relatives that have colon cancer
• Two consecutive generations with colon cancer (for instance, your mother and your grandmother on your mother’s side)
• One of these relatives is diagnosed before the age of 50

The American Cancer Society (ACS) explains that this syndrome can be caused by a mutation in any of several mismatch repair (MMR) genes, including MLH1, MSH2, MSH6, PMS1, and PMS2. “These genes are normally involved in repairing damaged DNA. When one of these genes isn’t working, cells can develop mistakes in their DNA, which might lead to other gene mutations and eventually cancer,” according to the ACS. The accumulation of these errors is known as High Microsatellite Instability (MSI-H).

What are the estimated cancer risks associated with Lynch syndrome?

Estimated general lifetime cancer risks for people with Lynch syndrome:

• Colorectal cancer 20% – 80%
• Endometrial cancer 15% – 60%
• Ovarian cancer 1% – 38%
• Stomach cancer 1% – 13%
• Hepatobiliary tract cancer (liver/bile duct/gallbladder) 1% – 4%
• Urinary tract cancer (kidney, ureter, bladder) 1% -18%
• Small bowel cancer (intestines) 1% – 6%
• Pancreatic cancer 1% – 6%
• Brain 1% – 3%

I have Lynch syndrome. What’s next?

If you test positive, you’ll need to undergo earlier screening for colon cancer, starting at age 20 to 25 years. Dr. Ophira Ginsburg, formerly a medical oncologist at NYU Langone’s Perlmutter Cancer Center and now a Senior Scientific Officer at the National Cancer Institute, says: “Colon cancer is something that really should be completely preventable through screening and appropriate interventions, like removal of polyps for example. So, individuals who carry one of the genes that’s associated with Lynch syndrome can be offered testing, certainly screening, at a much earlier age than you normally would have suggested by your care provider, even as early as the age of 25. We also would screen with a colonoscopy much more frequently.”

How can I prevent endometrial cancer?

The American College of Obstetricians and Gynecologists suggests endometrial biopsy every one to two years beginning at age 30 to 35 years. You should promptly seek medical attention if you have abnormal uterine bleeding.  You can consider having your uterus and ovaries removed to prevent endometrial and ovarian cancer, but this will make you unable to naturally conceive a child.

Should I have my entire colon removed?

The lifetime risk of colorectal cancer in people with Lynch syndrome can be as high as to 80% – 90%. But the removal of the large intestine (prophylactic colectomy) is not routinely recommended to prevent cancer from happening, unless you already have the diagnosis of colon cancer.

• If you have Lynch syndrome and a colon cancer, it’s best that you have the large intestine removed.
• If you are diagnosed with Lynch syndrome but do not have colon cancer, a prophylactic colectomy is not routinely recommended.

What about my family?

If you are diagnosed with Lynch syndrome you should ask your doctor whether your relatives should be referred for genetic counseling and testing for the familial mutation that causes Lynch syndrome. Testing in children should be offered 10 years before the earliest age of cancer onset in the family or by age 20 to 30 years.

What to ask your doctor

If you are concerned about your risk of colorectal cancer or other types of cancer, discuss it with your health care provider team. You can consider asking them the following questions:

• What is my risk of developing colorectal cancer or other types of cancer?
• What can I do to reduce my risk of cancer?
• What are my options for cancer screening?
• Does my family history increase my risk of colorectal cancer or other types of cancer?
• Have MSI or MMR tests been done on my tumor tissue?
• Should I meet with a genetic counselor?
• Should I consider genetic testing?
• Should I have my uterus and ovaries removed?
• Should I have my entire colon removed?