The stool DNA test works on the principle of exfoliation — it detects DNA in cells shed into the colon from the surface of cancer and precancer. The test targets a panel of DNA markers for all types of colorectal cancer and precancer with exquisite accuracy. Yet this remarkably sophisticated, high-performance molecular assay is extraordinarily simple for the patient. There is no bowel preparation, no diet or medication restrictions, and no uncomfortable procedure. In addition, there’s no need for a prerequisite visit to your health care provider.