Hereditary non-polyposis colorectal cancer

Hereditary non-polyposis colorectal cancer (HNPCC), also known as Lynch syndrome, is an autosomal dominant condition which predisposes to a host of malignancies, including colorectal carcinoma. It is considered the most frequent form of hereditary colorectal cancer. Diagnosis requires evaluation using clinical criteria (see: Amsterdam criteria for HNPCC).

Lynch syndrome is the most common cancer syndrome, affecting 1 in 400 persons 3. Typically HNPCC patients present in their forties and fifties with colorectal cancer 2, or with one of the associated malignancies. It is 5 times more common than familial adenomatous polyposis syndromes (FAP) 6. It is the most common hereditary cause of endometrial cancer 9.

HNPCC is due to mutations in DNA mismatch repair (MMR) genes 2, resulting most frequently in colorectal carcinoma (10-82% lifetime risk 9) as well as extracolonic malignancies, including 1,2:

There is a described association with breast malignancy, although the relationship is inconsistent 9. The MMR genes most commonly affected are MLH1, MSH2 (these two 70-85% of cases, MSH6, and PMS2 or EPCAM, an upstream gene in MSH2 expression 3.

Radiographic features are related to the underlying conditions:

The high risk of colorectal carcinoma warrants screening of the colon every 1 to 2 years starting from 25-40 years of age 2,3 and may require colectomy. With close surveillance and resection of any adenomas which develop, the risk of CRC can be reduced by 60% 3.

Due to a high number of extracolonic tumors, various screening programs have been instituted. Examples include transvaginal ultrasound screening of the uterus and ovaries (in post-menopausal women 9, at the clinician's discretion) and serum CA-125 2. One follow up regimen recommends annual transvaginal ultrasound and endometrial biopsy 3, although screening should be individualized 9.

Lynch syndrome was first described by Aldred Scott Warthin (1866-1931) 8, an American pathologist, from University of Michigan in Ann Arbor, Michigan, in 1913, after research into a family with several members with cancers. In the mid 1960s, Henry T Lynch (1928-fl.2019), an American oncologist, published further detailed painstaking work on the same family studied by Warthin, shedding further light on these apparently hereditary cancers 7. The condition was later renamed after Lynch who doggedly pursued the then heterodoxy that cancer could be hereditary.

Article information

rID: 1614
Section: Syndromes
Synonyms or Alternate Spellings:
  • Hereditary non polyposis colorectal cancer (HNPCC)
  • Hereditary non polyposis colorectal cancer
  • Lynch syndrome
  • Hereditary non-polyposis colorectal carcinoma
  • Lynch II syndrome

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Cases and figures

  • Case 1: duodenojejunal adenocarcinoma
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