When cells divide, they must make an exact replica of their genetic code, their DNA, so that the two resulting cells are identical. Lynch syndrome is an inherited defect in one of the four genes responsible for repairing errors that occur naturally during DNA replication, the so-called mismatch repair genes. If replication errors are not repaired, genetic defects, or mutations, are inherited by daughter cells that alter cell growth, differentiation and self-destruction, leading to an increased risk of cancer.
A person with Lynch syndrome has more than a 50:50 chance of developing cancer during their lifetime, most commonly bowel and womb cancers. Some people with Lynch syndrome develop more than one cancer during their lifetime, often at a younger age than other people.
When people know they have Lynch syndrome, they can have regular bowel tests, colonoscopies, to find and remove polyps before they develop into cancer. This has been shown to save lives. They can also protect themselves from womb cancer by having a hysterectomy once their family is complete. Taking an aspirin every day can reduce cancer risk in Lynch syndrome, although more research is needed to find out what dose is optimal. A diagnosis of Lynch syndrome can also allow family members to be tested and enrolled in cancer screening and prevention programmes, if they too test positive.