Lynch Syndrome: Three Facts about the Leading Cause of Hereditary Colorectal Cancer

By Carol Guzman

Lynch syndrome (LS) is a heritable disorder that causes an increased risk of colorectal and many other types of cancers. People inherit Lynch syndrome in an autosomal dominant manner, which means that if one parent carries a gene mutation for LS, there is a 50 percent chance LS will pass to each child. When they’re working as they should, the genes associated with LS protect you from getting certain cancers by repairing mistakes made in DNA, but mutations in these genes prevent them from working properly, which can lead to uncontrolled cell growth.

One in 440 Americans are carriers for Lynch syndrome.¹ Ashkenazi Jews have specific LS founder mutations and have among the highest rates of colorectal cancer of any ethnic group.^2,3 In honor of Colorectal Cancer Awareness Month and National Lynch Syndrome Awareness Day, here are three facts you might not have known about Lynch Syndrome:

Genes associated with LS can increase risk of breast and ovarian cancer.^4,5 In addition to a higher risk of colorectal cancers, women with specific variants of LS are twice as likely to develop breast cancer than women without Lynch syndrome (15%). Women can have up to a 24 percent increased risk of ovarian cancer with specific variants of LS.
Lynch syndrome is the leading cause of hereditary colorectal cancer (CRC).^6,7 According to the American Cancer Society (ACS), 5 percent of CRC cases are associated with inherited genetic mutations. ACS estimates that there will be 145,000 new cases of colorectal in 2019 and LS will account for approximately 2 – 4 percent of these cancer cases.
An accurate family health history is the best identifier of Lynch syndrome.⁸ Only 1 percent of the estimated 800,000 Americans with LS know they have the disorder. Patients do not typically find out they have LS until after a colorectal cancer diagnosis. Doctors do not recommend CRC patients get genetic screening for LS because of the rarity of the syndrome. Accurate family health history records remain the best strategy for identifying LS.

If you have Lynch Syndrome, talk to your doctor about how you can reduce your chances of getting cancers in the future. Having Lynch syndrome increases your chances of getting colorectal, stomach, pancreatic, urinary tract, pancreas, brain, small bowel, endometrial, breast, ovarian and uterine cancers.

Learn more about family health history and find tools and worksheets to help you collect key information on our family health history page. If you have questions about your genetic health, reach out to Sarnoff Center or your doctor.