Lynch syndrome is an autosomal dominant cancer predisposition syndrome characterized by an increased risk for colon cancer and cancer of the stomach, small intestine, upper urinary tract, liver, brain and skin. Women with this condition also have an increased risk for cancer of the lining of uterus (endometrium) and ovaries.

If you have concerns about your family history of colon or endometrial cancer, bring them up with your doctor. Together, you and your doctor may consider having a genetic evaluation of your family history and your cancer risk.

If a family member has been diagnosed with Lynch syndrome, tell your doctor. Ask to be referred to a genetic counselor. Genetic counselors are trained in genetics and counseling. They can help you understand Lynch syndrome, what causes it and what type of care is recommended for people who have Lynch syndrome. A genetic counselor can also help you sort through all the information about the disease and help you understand whether genetic testing is appropriate for you.

Lynch syndrome runs in families in an autosomal dominant inheritance pattern. This means that if one parent carries a gene mutation for Lynch syndrome, there's a 50 percent chance that mutation will be passed on to each child. The risk of Lynch syndrome is the same whether the gene mutation carrier is the mother or father or whether the child is a son or daughter.

How gene mutations cause cancer

The genes affected in Lynch syndrome are responsible for correcting changes in the genetic code (mismatch repair genes).

Your genes contain DNA, which carries instructions for every chemical process in your body. As your cells grow and divide, they make copies of their DNA and it's not uncommon for some minor mistakes to occur.

Normal cells have mechanisms to recognize mistakes and repair them. But the cells of people who inherit one of the abnormal genes associated with Lynch syndrome lack the ability to repair these minor mistakes. An accumulation of these mistakes leads to increasing genetic damage within cells and eventually can cause the cells to become cancerous.

If you have Lynch syndrome, be sure to get regular screenings in order to find any cancers at their earliest stages, when they’re easiest to treat. Colon cancer is 90% curable when you catch it early. If you’re at risk, you should start getting checkups much earlier than usual.

Your screening schedule will depend on your family history and whether you’ve had DNA testing. Here are some general guidelines:

• Colonoscopies every 1 to 2 years, beginning at age 20 to 25. This test uses a long scope to look for polyps in your colon. People with Lynch syndrome often get polyps that are harder to see. So you may need to have a high-definition colonoscopy or a chromoendoscopy, which uses dyes to color the polyps. A colonoscopy may show polyps before they become cancer.
• Endoscopies every 3 to 5 years, starting in your early to mid-30s. Both men and women can get an endoscopy to look in their stomach or intestines for signs of cancer.
• Pelvic exams, uterine biopsies, or transvaginal ultrasounds to check your uterus and ovaries once a year starting around age 30. Your doctor may also recommend blood tests to check how well your liver is working.

Some people with Lynch syndrome choose to have their colon taken out to help prevent cancer later on. Women who don’t want children in the future may also have their uterus and ovaries removed.

Lynch syndrome is passed down from parents to children through problem genes. People who have it have about a 40% to 80% chance of getting colorectal cancer by age 70. They’re also at risk for cancer of the uterus, ovaries, or stomach. And they tend to get cancer at younger ages than other people, often in their 30s and 40s.