Phenotype and cancer risk of various polyposis syndromes.

The gastrointestinal polyposis syndromes are disorders with multiple intestinal polyps. Three of these disorders, familial adenomatous polyposis, Peutz-Jeghers syndrome and juvenile polyposis are associated with increased risk of colorectal as well as extracolonic cancers. A description of the phenotype and associated cancer risk is provided for each.