Hereditary colorectal cancer associated with polyposis syndromes.

This study reviews different aspects of hereditary colorectal cancer associ ated with three polyposis syndromes: familial adenomatous polyposis, juveni le polyposis coli and Peutz-Jeghers syndrome. All these syndromes share som e similarities: low incidence, autosomal dominant inheritance, genetic pred isposition to colorectal cancer and/or other extracolonic cancers. Classica l familial adenomatous polyposis is clinically defined by the presence of h undreds of adenomatous polyps in the colon and rectum, whereas less than 10 0 polyps are found in attenuated familial adenomatous polyposis. Without pr ophylactic colectomy, colorectal cancer develops inevitably by the age of 4 0. Restorative proctocolectomy with ileal anal-pouch anastomosis is the ope ration of choice in familial adenomatous polyposis. In juvenile polyposis c oli, 50-200 hamartomatous polyps are found in the colon, rectum, stomach an d small bowel. Life-time cumulative risk for colorectal cancer is estimated to be 50%. Prophylactic colectomy is required only in cases in which endos copic surveillance is not able to control polyp development. Hereditary mix ed polyposis syndrome is a variant form of juvenile polyposis coli, consist ing of multiple mixed adenomatous, hyperplastic and hamartomatous polyps. P eutz-Jeghers syndrome is characterized by multiple hamartomatous polyps loc ated in the small bowel, colon and stomach. Small bowel follow through and colonoscopy is advised far surveillance. Surgery is warranted only in cases of polyps larger than 1 cm. The causative genes of these syndromes have be en cloned. Molecular genetic testing of affected and at-risk individuals is proposed in order to advise surveillance and management.