Hereditary colon cancer: Colonic Polyposis syndromes

In the U.S., the lifetime risk of colorectal cancer among both men and women is approximately 6% [1]. Although as many as 25% of colorectal cancers are associated with a family history of the disease, approximately 3-5% of cases arise in the setting of well-described familial genetic syndromes [2]. The most prevalent familial colorectal cancer syndrome is Lynch syndrome or hereditary nonpolyposis colorectal cancer (HNPCC). Patients with Lynch do not present clinically with an unusually heavy burden of adenomatous polyps, the precursor to the vast majority of colorectal cancers. On the other hand, the remaining 1-2% of hereditary colorectal cancer syndromes are characterized by significant polyposis. These syndromes can be broadly classified as adenomatous polyposis syndromes, hamartomatous polyposis syndromes, and the hyperplastic polyposis syndrome (Table 5.1). In this chapter, we review the salient clinical and genetic features of each of these polyposis syndromes.