This week, the Food and Drug Administration approved a new colorectal cancer screening test called Cologuard, a stool-based test. While there are other stool-based screening tests, Cologuard is the first to use a particular non-invasive method in detecting colorectal cancers and potentially cancerous polyps. The study results, which led to the approval, were recently published in the New England Journal of Medicine. You can read the full article here.The trial looked at more than 10,000 individuals who were at average risk of colorectal cancer and between the ages of 50 and 84 years old. The participants used either Cologuard or another type of stool test called a fecal immunochemical test. Cologuard detected 92 percent of colorectal cancers and 42 percent of advanced large polyps, compared with 74 percent and 24 percent, respectively. However, Cologuard did have a higher number of false positives, incorrectly identifying people who were negative for cancer or large polyps called adenomas (87 percent versus 95 percent). An individual's physician would need to order the test, but the kit is mailed directly to the person's residence. The person collects the sample and mails the kit back to the company using a prepaid mailer. Results are sent to the physician, who then contacts the patient for follow-up. The test looks for biomarkers in the stool sample that indicate the presence of cancerous cells and blood. As stool moves through the large intestine and rectum, it absorbs cells from large pre-cancerous polyps. By testing the stool using known biomarkers, Cologuard can detect blood cells and polyp cells that contain colorectal cancer-related mutations in its DNA. While the test accurately detects potential cancer, individuals who have a positive result would need to undergo a colonoscopy to confirm the polyp or cancerous mass. Current guidelines for colorectal cancer, which include fecal occult blood tests, sigmoidoscopy, and colonoscopy, do not include the new screening test. However, that may soon change. The Centers for Medicare and Medicaid Services issued a proposed national coverage determination for the test and is expected to be issuing a coverage ruling before the end of the year. Updated guidelines may follow. Unlike sigmoidoscopy and colonoscopy, the Cologuard test is not invasive and does not require the prep process that many people find uncomfortable. The new test may ultimately improve the rates of colon cancer screening and hence lower cancer incidence over time. The test's maker has set the price for the test at around $600. Study authors mentioned in the NEJM article that offering a choice among tests may improve the uptake of screening. "A non-invasive test with a high single-application sensitivity for curable-stage cancer may provide an option for persons who prefer noninvasive testing." Routine colorectal cancer screening is effective at lowering rates of colorectal cancer and death from the disease. Several groups, including the U.S. Preventive Services Task Force and the American Cancer Society, recommend people of average risk begin screening at age 50. Individuals with a family history of colorectal cancer or a medical history that increases the risk of colorectal cancer should start screening at an earlier age.Updated 8/15/2014: One of our readers posed the question on when the test would become available. We reached out to the test's maker, Exact Sciences, and received this statement from CEO Kevin Conroy: "Exact Sciences is able to take orders for Cologuard today in the U.S. The company is completing the expected and appropriate packaging and logistical activities that are normal immediately following FDA approval. The company should be able to process orders in the very near future."