Colon Cancer

HNPCC is an autosomal dominant disorder that may be responsible for up to 5 percent of colon cancers. The genetic mutation leading to the abnormality is the mutation of DNA mismatch repair genes. Individuals with this mutation have up to an 80 percent chance of developing colon cancer. At least five genes are involved in this syndrome.

Malignancy in patients with HNPCC occurs at a younger age than in the general population, is more often located in the proximal colon (the portion nearest the small intestine), and may be associated with multiple tumors. HNPCC also carries an increased risk of tumors of the endometrium, ovaries, stomach, small intestine, bile ducts, bladder, renal pelvis, and ureters. Genetic testing is useful for HNPCC families.