Hereditary Non-Polyposis Colon Cancer (HNPCC) or Lynch Syndrome
Lynch Syndrome is an inherited colorectal cancer-related syndrome that accounts for close to 3% of all colorectal cases. This genetic disorder is caused by alterations in the ‘mismatch repair genes’. Those with mutations in these genes have up to an 80% certainty of developing colon cancer without intervention. The average age of diagnosis is 45 years. Lynch Syndrome increases the likelihood of developing other types of cancer, such as cancers of the small bowel, stomach, uterus, ovaries, urinary system and biliary tract. A careful review of personal and family history alerts physicians to patients who may have Lynch Syndrome but do not realize it. Colonoscopy, and for women close surveillance of the ovaries and uterus, are important screening tools for those diagnosed with Lynch Syndrome. Other tests sometimes done based on family history, include upper endoscopy and evaluation of the urinary tract. Preventive surgery is a consideration for those with this condition. Those who meet diagnostic criteria should consider genetic counseling and testing.
FAP (Familial Adenomatous Polyposis)
FAP is an inherited colorectal cancer-related condition that accounts for close to 1% of all colorectal cancer cases. The APC gene is known to be associated with this disorder. For those with FAP, numerous polyps develop throughout the colon and in some patients, in the stomach and small intestine. These polyps often begin to form in childhood. Without intervention, nearly 100% of those with FAP will develop colorectal cancer by age 40. Additional symptoms may include development of desmoid tumors, osteomas (benign bony growths), benign skin changes, congenital findings involving the retina (eye). There is an increased risk of other cancers, such as thyroid, stomach, and small intestine. A review of personal and family history alerts physicians to patients who may have FAP but do not realize it. Early colon screening to detect polyps is an important tool for those diagnosed with FAP. Surgery is required for removal of the colon; individual removal of the polyps is impossible due to the vast number of them. Those who meet diagnostic criteria should consider genetic counseling and testing.
The Cancer Risk and Prevention Clinic provides cancer genetic risk assessment and counseling. These services are available with a physician referral.