New guidelines from the U.S. Multi-Society Task Force (MSTF) on Colorectal Cancer recommend universal genetic testing of newly diagnosed colorectal tumors to identify Lynch syndrome, a genetic condition that causes most inherited colorectal cancers. About 3% of those diagnosed with colorectal cancer each year have Lynch syndrome, according to “Guidelines on Genetic Evaluation and Management of Lynch Syndrome: A Consensus Statement by the U.S. Multi-Society Task Force on Colorectal Cancer,” which was published in Gastroenterology.​ MSTF, a consortium of four medical associations, made the universal genetic testing recommendation based on studies of colorectal cancer molecular testing which show that up to 28% of Lynch syndrome cases would be missed based on the most liberal clinical criteria.

Genetic testing is recommended to look for signs of mismatch repair (MMR) deficiency, which helps identify those with Lynch syndrome. Genetic testing of tumors in those newly diagnosed with colorectal cancer for evidence of MMR deficiency has greater sensitivity than other methods to identify Lynch syndrome, including the Bethesda guidelines and a selective tumor testing strategy. It is also considered cost-effective.

When used appropriately, the guideline states, genetic testing for Lynch syndrome can confirm the diagnosis at the molecular level, justify surveillance of those at-risk, decrease the cost of surveillance by identifying those at highest versus lowest risk, facilitate clinical management of patients with Lynch syndrome, and guide patients and families in their family and career planning. The group cautioned that if used inappropriately, genetic testing can misinform affected patients with false-negative results while also wasting patient and societal resources.

Those who have or are at risk for Lynch syndrome should also undergo more frequent screenings for colorectal, ovarian, and endometrial cancers. Other preventive measures may also be recommended depending on age and health status. Aspirin therapy and removal of the large intestine are two treatments suggested for those who have Lynch syndrome, according to the task force.