Hereditary nonpolyposis colorectal cancer, often called HNPCC or Lynch Syndrome, is an inherited cancer syndrome that affects the digestive tract, reproductive tract and other major organs. People with Lynch Syndrome have an increased risk of cancers of the stomach, small intestine, liver, gallbladder ducts, upper urinary tract, brain, skin, and prostate. Women with this disorder also have a greatly increased risk of endometrial and ovarian cancer.
Colon cancers develop from adenomatous polyps that occur at an earlier age than do colon polyps in the general population. Although previously thought of as a disease presenting in adulthood, teenagers from Lynch syndrome families can develop active symptoms, including colon cancers. Lynch Syndrome adenomas do not develop in large numbers but progress to cancer more quickly than the occasional adenomas found in otherwise healthy people.
Lynch Syndrome is caused by a genetic mistake, or mutation, in one of four blueprint genes that make DNA repair proteins. When the DNA repair system does not work properly, harmful DNA mistakes are passed on as the cells multiply leading to disorganized growth and the development of cancer. Although mutations in these genes predispose individuals to cancer, not all people who carry these mutations develop cancerous tumors.
Careful follow-up, including examination of the large intestine or colon (colonoscopy), have been shown to reduce the risk of this disease.