The Lynch syndrome is the most common inherited syndrome associated with colorectal cancer, accounting for 3% of new diagnoses; it is also associated with extracolonic cancers, the most common of which is endometrial cancer.
The Lynch syndrome phenotype includes a propensity for cancers of the proximal colon, poor tumor differentiation with mucinous or signet-ring cell histologic features or a medullary growth pattern, abundant infiltrating lymphocytes in the tumor, and synchronous and metachronous colorectal cancers.
Guidelines for Diagnosis of the Lynch Syndrome
Amsterdam II criteria
1. Three or more relatives with histologically verified Lynch syndrome–associated cancer, one of whom is a first-degree relative of the other two*
2. Cancer involving at least two generations
3. One or more cancer cases diagnosed before 50 years of age
Revised Bethesda guidelines
1. Diagnosis of colorectal cancer or endometrial cancer in a patient younger than 50 years of age
2. Presence of synchronous colorectal cancers, metachronous colorectal cancers, or other Lynch syndrome–associated tumors, regardless of patient age
3. Diagnosis of colorectal cancer with a high frequency of microsatellite instability on the basis of histologic findings (Crohn’s-like lymphocytic reaction, mucinous or signet-ring cell differentiation, or medullary growth pattern) in a patient younger than 60 years of age
4. Diagnosis of colorectal cancer in one or more first-degree relatives with a Lynch syndrome–related tumor, with one of the diagnoses occurring before 50 years of age
5. Diagnosis of colorectal cancer in two or more first- or second-degree relatives with Lynch syndrome–related tumors, regardless of patient age
* Lynch syndrome–associated tumors include cancers of the colon and rectum, endometrium, stomach, ovary, pancreas, ureter, renal pelvis, biliary tract, brain, small bowel, and sebaceous glands, as well as keratoacanthomas.
- Sinicrope FA. Lynch Syndrome-Associated Colorectal Cancer. N Engl J Med. 2018 Aug 23;379(8):764-773. [Medline]
- Stoffel EM, Mangu PB, Gruber SB, Hamilton SR, Kalady MF, Lau MW, Lu KH, Roach N, Limburg PJ; American Society of Clinical Oncology; European Society of Clinical Oncology. Hereditary colorectal cancer syndromes: American Society of Clinical Oncology Clinical Practice Guideline endorsement of the familial risk-colorectal cancer: European Society for Medical Oncology Clinical Practice Guidelines. J Clin Oncol. 2015 Jan 10;33(2):209-17 [Medline]
Created Mar 18, 2019.