What is Lynch syndrome?

What you’ll learn in this article:

• Lynch syndrome is one of the most common hereditary colorectal cancer conditions
• There are screening and prevention guidelines for people with a variant in one of the Lynch syndrome genes
• MyHealth: STEP ONE analyzes the Lynch syndrome genes

Lynch syndrome is a hereditary condition that causes a person to be more likely to develop certain types of cancer compared to the general population. The odds vary depending on the organ in question. For instance, over the course of a person’s lifetime, an individual with Lynch syndrome has roughly a 52-82% chance of developing colon cancer. That same person’s odds of developing gastric cancer are approximately 6-13%.

How is Lynch syndrome inherited?

Over the past 20 years, scientists have identified five primary genes for which certain variants cause Lynch syndrome: MLH1, MSH2, MSH6, PMS2, and EPCAM. It is passed down in the family as an “autosomal dominant” disorder, meaning that both men and women can have Lynch syndrome, can inherit it from their mother or father, and can pass it on to their sons or daughters. It also means that the odds of passing it on are always 50/50 for each individual offspring (with the exception of identical twins who would both inherit it or both not inherit it).
Lynch syndrome is relatively common. It’s estimated that 1-6% of people with colon cancer, and approximately 1% of women with endometrial cancer, have Lynch syndrome. All told, approximately 1 out of 440 people have the condition, affecting anywhere from 200,000-300,000 Americans. Fortunately, once someone who has Lynch syndrome is identified, it’s possible to identify the other people in the family who also have it because it is a hereditary condition. This means that more individuals can get the screening, prevention, or treatment they need.

Treatment and prevention options

Some types of cancer associated with Lynch syndrome—like pancreatic cancer—are not highly preventable at present. But most types are preventable to some degree. For instance, men and women who have Lynch syndrome are at increased risk for colon cancer, so medical guidelines recommend getting colonoscopies at a younger age and more regularly than the general population. Women who have Lynch syndrome have an increased risk of developing ovarian and/or endometrial cancer as well. Here, preventative surgery can lower their odds of developing these types of cancer relative to that of the general public, although it does not completely eliminate the possibility of cancer stemming from those tissues. And in the case of pancreatic cancer, individuals who test positive for Lynch syndrome can sometimes qualify for a clinical trial that is looking for new ways to screen and/or prevent pancreatic cancer.

References:

Kohlmann, Wendy. “Lynch Syndrome.” Advances in Pediatrics., U.S. National Library of Medicine, 12 Apr. 2018, www.ncbi.nlm.nih.gov/books/NBK1211/.