One in 35 people who have colorectal cancer also have Lynch syndrome, which translates to about one in 370 people in the general population. Although not everyone with Lynch syndrome will develop cancer, Lynch syndrome (previously referred to as hereditary nonpolyposis colorectal cancer syndrome) is the most common heritable colorectal cancer syndrome and accounts for 2% to 3% of colorectal cancers.
According to the Fight Colorectal Cancer organization, as many as 98% of people and 90% of families are unaware that they have Lynch syndrome. People with Lynch syndrome are at increased risk not only of colorectal cancer, but other cancers as well (eg, stomach, pancreas, genitourinary, brain). Women with Lynch syndrome face a 40% to 60% chance of developing uterine cancer as well as an increased risk of ovarian cancer.
The American Gastroenterological Association (AGA) Institute issued recommendations on the diagnosis and management of Lynch syndrome in July 2015. They include a Clinical Decision Support Tool for people newly diagnosed colorectal cancer and patients with family history suggestive of Lynch syndrome.
The AGA recommends use of a risk prediction model for patients with a history suggestive of Lynch syndrome but no personal history of cancer and testing of tumors for genetic mutations when people are diagnosed with colorectal cancer. They recommend surveillance colonoscopy every 1-2 years for patients with Lynch syndrome as well as aspirin chemoprevention. The complete AGA Guidelines are available at http://www.gastrojournal.org/article/S0016-5085%2815%2901031-8/fulltext