Dr. Benson on MSI Testing in Colorectal Cancer

Al B. Benson, MD, professor of medicine, Hematology and Oncology, Northwestern University Feinberg School of Medicine, discusses the implications of microsatellite instability (MSI) testing on patients with colorectal cancer (CRC).

It is important, according to Benson, to perform tumor testing to determine whether a patient with CRC has an alteration, as that may inform treatment decisions. MSI testing should be done on every patient with CRC to ensure the patient does not have a genetic component, such as Lynch syndrome, explains Benson.

Patients with microsatellite instability—high (MSI-H) tumors are candidates for immunotherapy, which is generally given after progression on first-line chemotherapy, adds Benson. However, ongoing clinical trials are also examining first-line immunotherapy in this patient population. MSI testing is necessary regardless of the stage of disease, concludes Benson.