Genetic counseling and cascade genetic testing in Lynch syndrome

Lynch syndrome is the most common cause of inherited colorectal and endometrial cancers. Individuals with Lynch syndrome have a 10–80 % lifetime risk for colorectal cancer and a 15–60 % lifetime risk for endometrial cancer. Both cancers are preventable through chemoprevention, intensive cancer surveillance, and risk-reducing surgery options. Efforts to identify as many individuals with Lynch syndrome as possible will prevent cancers and save lives. This includes the traditional cancer genetic counseling model whereby individuals with and without cancer are evaluated for a possible Lynch syndrome diagnosis based on their personal and family history of colon polyps and cancers. It also includes universal tumor screening for Lynch syndrome whereby all individuals with colorectal or endometrial cancer are screened for tumor features of Lynch syndrome at the time of diagnosis. Those with tumors suspicious for Lynch syndrome are referred for cancer genetic counseling regardless of their family history of cancer. This two approaches must be maximized to attain high patient reach. Finally, and perhaps most importantly, cascade testing among the at-risk relatives of those diagnosed with Lynch syndrome is critically important to maximize the diagnosis of individuals with Lynch syndrome. In fact, the cost-effectiveness of universal tumor screening for Lynch syndrome relies entirely on counseling and testing as many at-risk individuals as possible since young unaffected individuals stand to benefit the most from an early diagnosis of Lynch syndrome. This approach must be optimized to achieve high family reach. It will take a concerted effort from patients, clinicians and public health officials to improve current approaches to the diagnosis of Lynch syndrome and the prevention and treatment of Lynch syndrome-associated cancer but these lessons can be applied to other conditions as the ultimate example of personalized medicine.