All colorectal cancer patients should undergo testing for Lynch syndrome, according to new guidelines from the American Gastroenterological Association (AGA). These guidelines were published in Gastroenterology, the official journal of the AGA.
Most cases of colorectal cancer are sporadic, but approximately 3-5 percent of cases are due to Lynch syndrome, a hereditary disorder that increases an individual’s chances of developing cancer of the digestive tract, gynecological tract or other organs. Patients who have Lynch syndrome have an 80 percent higher risk of developing colorectal cancer.
The majority of patients who have Lynch syndrome are unaware that they have it. “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,” says lead guideline author Joel H. Rubenstein, MD, AGAF, research scientist at the Veterans Affairs Center for Clinical Management Research and associate professor, division of gastroenterology at the University of Michigan Medical School (Source: HCP Live).
The new guidelines are as follows:
Patients who have a family history of Lynch syndrome but no personal history of cancer should have the option of risk prediction modeling for testing in lieu of doing nothing. Physicians may also offer risk prediction model ling for testing instead of directly proceeding to germline testing.
Colorectal cancer patients should have tumors tested either with immunohistochemistry (IHC) or for microsatellite instability (MSI), as Lynch syndrome tumors display high MSI.
Colorectal cancer patients with IHC absent for MLH1 – 75 percent of whom will have sporadic cancers rather than Lynch syndrome – should have tumors tested for BRAF mutation or hypermethylation of the MLH1 promoter. If the patient displays neither, proceed to germline testing for Lynch syndrome.
Patients with Lynch syndrome can choose to undergo surveillance colonoscopy with repeat procedures every one to two years, rather than less frequent intervals. Aspirin can also be offered to these patients as cancer chemoprevention (Source: American Gastroenterological Association).
According AGA estimates, 30 percent of colorectal cancer patients have a family history of the disease, and Lynch syndrome is the most common inherited cause of colorectal cancer. While not all people with Lynch syndrome will develop cancer, they have genetic mutations which make them more likely to develop certain types of cancer such as colorectal cancer and endometrial cancer.