Physician and Healthcare Provider Information

Lynch Syndrome

In both men and women, colorectal cancer is the third most commonly diagnosed cancer in the United States. Each year almost 150,000 people are diagnosed with it and over 50,000 individuals will die from colon cancer. 25% of individuals diagnosed with colon cancer have a significant family history of cancer and approximately 1 in every 35 colon cancer patients have Lynch Syndrome.

Lynch Syndrome is an autosomal dominant hereditary colon cancer Syndrome cause by mutations in 1 of 4 mismatch repair genes (MLH1, MSH2, MSH6 and PMS2). The MLH1 and MSH2 genes are the two most common causes of Lynch Syndrome with the MSH6 and PMS2 genes account for less. These are genes that help repair damage to other genes. If this damage is not repaired, the cell may die or grow uncontrolled. The latter option is the cause of cancer.

The average age of onset of colon cancer in Lynch Syndrome is estimated to be 42 to 61 compared to 71 in the general population. There is some data to suggest that mutations in the MLH1 and MSH2 are in the earlier range, while mutations in the MSH6 and PMS2 genes lead to the later age of onset in the range discussed above.

A history of colon polyps warrants increased screening if these polyps are adenomatous rather than hyperplastic. While colon polyps normally grow slowly, in Lynch Syndrome, adenomas may rapidly transform into a cancerous growth. Colon cancers due to Lynch Syndrome are also frequently found on the right side of the colon. With the aggressiveness of Lynch Syndrome cancers, all suspicious lesions must be biopsied in a timely manner. For these reasons, Hemoccults, flexible sigmoidoscopies, barium enemas, and virtual colonoscopies are inappropriate screening tests for Lynch Syndrome. Instead yearly colonoscopies are indicated for Lynch Syndrome patients at a much earlier age.