Abstract
HNPCC (Lynch syndrome) is the most common form of hereditary colorectal cancer (CRC), wherein it accounts for between 2-7 percent of the total CRC burden. When considering the large number of extracolonic cancers integral to the syndrome, namely carcinoma of the endometrium, ovary, stomach, hepatobiliary system, pancreas, small bowel, brain tumors, and upper uroepithelial tract, these estimates of its frequency are likely to be conservative. The diagnosis is based upon its natural history in concert with a comprehensive cancer family history inclusive of all anatomic sites. In order for surveillance and management to be effective and, indeed, lifesaving, among these high-risk patients, the linchpin to cancer control would be the physician, who must be knowledgeable about hereditary cancer syndromes, their molecular and medical genetics, genetic counseling, and, most importantly, the natural history of the disorders, so that the entirety of this knowledge can be melded to highly-targeted management.
Highlights
The annual worldwide incidence of colorectal cancer (CRC) is approximately 944,717 and its worldwide mortality incidence is approximately 492,411
In order for surveillance and management to be effective and, lifesaving, among these high-risk patients, the linchpin to cancer control would be the physician, who must be knowledgeable about hereditary cancer syndromes, their molecular and medical genetics, genetic counseling, and, most importantly, the natural history of the disorders, so that the entirety of this knowledge can be melded to highly-targeted management
In hereditary nonpolyposis colorectal cancer (HNPCC), annual full colonoscopy initiated between ages 20 and 25 is recommended for those with strong clinical evidence and/or MLH1, MSH2, or MSH6 germline mutations
Summary
The annual worldwide incidence of colorectal cancer (CRC) is approximately 944,717 (males: 498,754; females: 445,963) and its worldwide mortality incidence is approximately 492,411 (males: 254,816; females: 237,595). Among hereditary CRC-prone syndromes with multiple colonic polyps (adenomatous, juvenile, PeutzJeghers, mixed [hamartomatous, hyperplastic, adenomatous]), the best known, namely familial adenomatous polyposis (FAP), accounts for less than 1% of the total CRC burden, while the other syndromes in this group combine to account for another fraction of a percent of the total CRC incidence [4, 5]. In contrast to those hereditary CRC disorders, hereditary nonpolyposis colorectal cancer (HNPCC), known as Lynch syndrome, represents 2-7% of the total CRC burden [6]. When collecting the cancer family history, as well as when interpreting the pedigree, an awareness of the cardinal features of hereditary cancer, as shown in Table 1, is extremely valuable
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