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Genetics of Colorectal Cancer (PDQ®): Genetics - Health Professional Information [NCI] - Major Genetic Syndromes

Table 8. Clinical Practice Guidelines for Diagnosis and Colon Surveillance of Familial Adenomatous Polyposis (FAP) continued...

Criteria for defining LS families

The research criteria for defining LS families were established by the International Collaborative Group (ICG) meeting in Amsterdam in 1990, and are known as the Amsterdam criteria.[240]

Amsterdam criteria:

  1. One member diagnosed with CRC before age 50 years.
  2. Two affected generations.
  3. Three affected relatives, one of them a first-degree relative of the other two.
  4. FAP should be excluded.
  5. Tumors should be verified by pathological examination.

These criteria provide a general approach to identifying LS families, but they are not considered comprehensive; a number of families who do not meet these criteria, but have germline MMR gene mutations, have been reported.[241,242]

To address these issues and to improve the diagnosis of LS clinically, the ICG developed revised criteria in 1999; these are known as Amsterdam criteria II.[243]

Amsterdam criteria II:

  1. There should be at least three relatives with a LS-associated cancer (CRC or cancer of the endometrium, small bowel, ureter, or renal pelvis).
  2. One should be a first-degree relative of the other two.
  3. At least two successive generations should be affected.
  4. At least one should be diagnosed before age 50 years.
  5. FAP should be excluded in the CRC cases.
  6. Tumors should be verified by pathological examination.

Although these criteria are among the most stringent used to identify potential candidates for microsatellite and germline testing, it must be cautioned that by definition, familial CRC type X includes families meeting Amsterdam criteria but in whom there is no evidence of MSI. (Refer to the Familial CRC type X section in the Major Genetic Syndromes section of this summary for more information.)

A third set of clinical criteria that can be used to identify LS families is the revised Bethesda guidelines.[244] The criteria was expanded to improve sensitivity in identifying families. The Bethesda guidelines are the least stringent for identifying families with germline mutations in one of the MMR genes. Because of lack of specificity for LS, the Bethesda guidelines are utilized to identify individuals whose colorectal tumors should be tested for MSI and/or IHC, rather than to identify families that meet clinical criteria for LS. (Refer to the Genetic/Molecular Testing for LS section in the Major Genetic Syndromes section of this summary for more information about testing for MSI and IHC.)

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