AGA: Test all patients with colorectal cancer for Lynch syndrome

Last Updated: 2015-09-14

By Reuters Staff

NEW YORK (Reuters Health) - A new guideline from the American Gastroenterological Association (AGA) recommends that all patients with colorectal cancer have their tumors tested for Lynch syndrome, the most common inherited cause of colorectal cancer.

"Approximately 50,000 Americans are expected to die from colorectal cancer this year, and hereditary syndromes account for a small, but important fraction of those diagnoses," Dr. Joel H. Rubenstein, lead author of the guideline, said in a statement.

"The majority of patients with Lynch syndrome are unaware that they have the syndrome. The AGA recommendation for tumor testing in all newly diagnosed cases of colorectal cancer to identify Lynch syndrome could be considered as a process measure to ensure that patients are receiving the highest-quality of care," said Dr. Rubenstein, research scientist at the Veterans Affairs Center for Clinical Management Research and associate professor, division of gastroenterology at the University of Michigan Medical School in Ann Arbor.

For patients without a personal history of colorectal or other cancer but with a family history suggestive of Lynch syndrome, the guideline says offer patients risk prediction modeling for testing, rather than doing nothing. It also says prediction models should be offered rather than proceeding directly with germline genetic testing. This is a "conditional" recommendation with "very low" quality of evidence.

For patients with colorectal cancer, the guideline recommends all patients have their tumors tested with either immunohistochemistry (IHC) or for microsatellite instability (MSI) to identify potential cases of Lynch syndrome versus doing no testing for Lynch syndrome. This is a "strong" recommendation with "moderate" quality of evidence.

For patients with colorectal cancer with IHC absent for MLH1, roughly 75% of whom will have sporadic cancers rather than Lynch syndrome, the AGA recommends second-stage tumor testing for a BRAF mutation or for hypermethylation of the MLH1 promoter rather than proceeding directly to germline genetic testing. (conditional recommendation, very low quality of evidence).

For patients with Lynch syndrome, surveillance colonoscopy is strongly recommended (moderate quality of evidence) at an interval of every one to two years (conditional recommendation, low quality of evidence). Lynch syndrome patients should also be offered aspirin as cancer chemoprevention (conditional recommendation, low quality evidence).

The full guideline, including a clinical decision support tool, appears in the September issue of Gastroenterology.

SOURCE: http://bit.ly/1LtDcNM

Gastroenterol 2015.