ORANGE, Calif. —  Doctors say more than 1 million people are walking around with Lynch syndrome and most don’t know they have it.

UCI Health Dr. William Karnes is a gastroenterologist whose expertise includes hereditary cancers such as Lynch syndrome, one of the most common hereditary conditions. He said those who test positive for it have a 60% to 80% greater chance of developing colon cancer.  

People with Lynch syndrome also have a higher risk of ovary, stomach, small intestine, hepatobiliary tract, upper urinary tract, brain and skin cancers.

Andrea Barnow tested positive and shares how she is monitoring her health with additional screenings.

Karnes said those who have a family history of cancers or have had cancer at a young age, 50 and under, should ask their physicians to get the simple saliva-based genetic test for Lynch syndrome.