Diagnosis and therapy of hereditary polyposis syndromes.

The hereditary polyposis syndromes include the adenomatous polyposis syndromes (familial adenomatous polyposis and Gardner syndrome, and Turcot syndrome) and the hamartomatous polyposis syndromes (Peutz-Jeghers syndrome, juvenile polyposis, and Cowden's disease). The adenomatous polyposis syndromes are characterized by numerous adenomatous polyps throughout the entire colon and a spectrum of extracolonic manifestations; they invariably progress to colorectal cancer without appropriate intervention. The hamartomatous polyposis syndromes are characterized by diffuse intestinal or colonic hamartomatous polyps, such as juvenile polyps. Although hamartomatous polyps have virtually no malignant potential, the hamartomatous polyposis syndromes are associated with increased risk of cancer, both within and outside the small intestine and the colon. Diagnosis of symptomatic polyposis is by colonoscopy, but in presymptomatic screening of familial adenomatous polyposis, genetic testing can be effective, and it is becoming increasingly available though research laboratories. Management involves treatment of affected individuals, counseling of patients and their families, screening of at-risk individuals, and surveillance of affected patients for extracolonic cancers. Treatment of adenomatous polyposis is primarily colectomy during the second or third decade. For the hamartomatous polyposis syndromes, surveillance for early cancers and their excision remain the only practical, although not totally satisfactory, approaches.