What does it mean to have a HNPCC gene mutation?
People who inherit a HNPCC gene mutation have up to a 75 percent chance of developing colorectal cancer by the age of 65. Mutation carriers who have already been diagnosed with colorectal cancer have an increased risk of developing a second colorectal cancer. This risk could be as high as 50 percent. Women who inherit a HNPCC gene mutation also have: • Up to a 40 to 60 percent lifetime risk of developing uterine (endometrial) cancer. This is in contrast to the general population’s risk for uterine cancer, which is approximately 3 percent. • A 5 to 15 percent lifetime chance of developing ovarian cancer. The general population’s risk for ovarian cancer is 1 to 2 percent. Colorectal and endometrial cancers are the most common malignancies reported in HNPCC families, but other cancers are associated with HNPCC mutations as well. These cancers can affect both men and women. They include cancers of the: • Stomach • Small intestine • Biliary system • Pancreas • Upper urinary (kidney and uret
