• Perhaps 6% of patients with cancer of the colon or rectum have HNPCC
• Most common form of hereditary colorectal cancer
• Gene responsible for this syndrome has been localized to chromosome 2p
• Lynch syndrome II:
-Early onset (average age 44)
-Synchronous and metachronous cancers and other associated extracolonic adenocarcinomas, especially endometrial carcinoma
• Lynch syndrome I: Hereditary site-specific colon cancer shows the same characteristics except that there are no extracolonic cancers
• Autosomal dominant inheritance
• Cancers arise in discrete adenomas but polyposis (ie, hundreds of polyps) does not occur
• Diagnostic criteria (Amsterdam criteria)
-Families must have at least 3 relatives with colorectal cancer, 1 of whom is a first-degree relative of the other 2
-Colorectal cancer must involve at least 2 generations, and at least 1 cancer case must occur before age of 50
• Adenomas and carcinomas in HNPCC arise at an early age
-Adenomas may occur in patients in their 20s and 30s, with a mean age for carcinoma development of 40 to 45 years
-Are often proximal in location and multiple
• Alterations in DNA mismatch repair genes that help maintain DNA fidelity during replication are characteristic of patients with HNPCC: (hMLH1, hPMS1 and hPMS2, and hMSH2, hMSH3, and hMSH6) may lead to the inability to repair base pair mismatches and result in DNA replication errors or microsatellite instability
• Accelerated carcinogenesis occurs in hereditary nonpolyposiscolorectal cancer compared with sporadic cases
• The frequency of HNPCC in the general population is yet to be determined, but HNPCC may account for as many as 6% of colorectal cancer cases
• Multiple generations are affected with colorectal cancer at an early age (mean, approximately 45 years) with a predominance of right-sided colorectal cancer (approximately 70% proximal to the splenic flexure)
• Excess of synchronous colorectal cancer and metachronous colorectal cancer
• Excess of extracolonic cancers—namely, carcinoma of the endometrium (second only to colorectal cancer in frequency), ovary, stomach (particularly in Asian countries such as Japan and Korea), small bowel, pancreas, hepatobiliary tract, brain, and upper uroepithelial tract
• As compared with sporadic colorectal cancer, tumors in HNPCC are more often poorly differentiated, with an excess of mucoid and signet-cell features
Log In to View More
If you don't have a subscription, please view our individual subscription options below to find out how you can gain access to this content.
Want remote access to your institution's subscription?
Sign in to your MyAccess profile while you are actively authenticated on this site via your institution (you will be able to verify this by looking at the top right corner of the screen - if you see your institution's name, you are authenticated). Once logged in to your MyAccess profile, you will be able to access your institution's subscription for 90 days from any location. You must be logged in while authenticated at least once every 90 days to maintain this remote access.
If your institution subscribes to this resource, and you don't have a MyAccess profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus.
AccessSurgery Full Site: One-Year Subscription
Connect to the full suite of AccessSurgery content and resources including more than 160 instructional videos, 16,000+ high-quality images, interactive board review, 20+ textbooks, and more.
Pay Per View: Timed Access to all of AccessSurgery
24 Hour Subscription $34.95
48 Hour Subscription $54.95
Pop-up div Successfully Displayed
This div only appears when the trigger link is hovered over.
Otherwise it is hidden from view.