gastrointestinal disorders
Lynch Syndrome
Key Points
Certain autosomal dominant mutations confer a 70 to 80% lifetime risk of developing colorectal cancer. Patients also have an increased risk of other cancers, particularly of the endometrium and ovary. Symptoms, initial diagnosis, and treatment are similar to other forms of colorectal cancer. Patients with colorectal cancer, particularly those with certain familial risk factors, should have their tumor tissue tested for microsatellite instability or with immunohistochemistry; if positive, genetic testing is done. Treatment is surgical resection with close endoscopic surveillance of any remaining colorectal mucosa. First-degree relatives who have not undergone genetic testing should have colonoscopy every 1 to 2 years beginning in their 20s, and annually after age 40; women should also be tested annually for endometrial and ovarian cancer. 