Biomarkers: The Next Revolution ~ The Doctor is IN with Dr. Frank MacMillan

By: Dr. Frank MacMillan – January, 2015

I’d like to be funny and say that my end of the year article is typically on the year’s major breakthrough in health and wellness, but I have never done a year-end health column before, so here are my thoughts on a major breakthrough that I believe is under reported and under the radar. Biomarkers are here and you should expect to hear a lot more in the near future. A biomarker is simply something made by a living organism found in blood, body fluid, or tissue that is a target for testing to see if a condition or disease is present. This is a really big deal and will positively affect you or someone you know in a way that could be life-changing.

The Center for Medicare Services (CMS) and the Food and Drug administration (FDA), recently announced parallel approval of the first commercially available test for colorectal cancer and polyps that can detect a collection of DNA markers that are naturally shed into the fecal stream by the tumor. The new test is called Cologuard, and it is a non-invasive test that can be done without a bowel prep or sedation or inconvenience. This is a significant advance because while colonoscopy is a safe and effective way to screen for polyps and cancer, approximately 50% of people eligible to have colonoscopy choose not to screen because of cost, perceptions of pain or embarrassment, or inability to complete a laxative bowel prep.

Colorectal cancer is the 2nd leading cause of cancer death in the USA, with 150,000 new cases and 50,000 deaths each year that are potentially preventable. While screening colonoscopy has made a major dent in this terrible disease, and in fact colonoscopy has saved the country $10 billion over the past 10 years due to prevention and early detection, it is also true that 50% of people eligible for screening fail to get a colonoscopy and remain at risk. CMS announced on October 9 that it would cover Cologuard for its members once every three years with certain restrictions.

The test will cost approximately $500, and be completely covered as a screening benefit for Medicare patients. Private insurance coverage is unknown at this time, but many insurance companies follow Medicare coverage decisions. Check with your insurance company to be certain.

The restrictions include limiting testing to individuals who meet “average risk screeing” criteria, or simply no high risk features. This is defined as age 50 to 85, no signs or symptoms of disease meaning no pain or bleeding, no anemia or blood in the stool, no personal history of polyps or cancer, no family history of polyps or cancer, no Crohn’s or colitis, no inherited polyp syndromes. Once the test is done, additional testing can be done for symptoms but not for “screening” (no symptoms and no personal or genetic risks) and cost sharing may apply.

So, how good is Cologuard testing? According to the Imperiale 2014 study (N Engl J Med 2014; 370:1287-1297) which led to FDA and CMS approval, it is 92.3% sensitive for detecting colon cancer, but 42% sensitive for advanced (still benign) precancerous polyps. Sensitivity improved for polyps in patients over the age of 65 to 44%. Specificity was also good at 89.8%. Unfortunately there is no perfect test and there are trade offs for cost, convenience, sensitivity and specificity. It should be restated that Cologuard is not an appropriate choice for patients at high risk. On the other hand, the relatively poor sensitivity for advanced polyps may be less of a concern for patients at “average risk” as advanced precancerous polyps are uncommon in this group of people.

The real good news however is that these tests will only get better with time, and we will be preventing and curing more cancers with the identification and commercialization of new and better biomarkers, not only for colon cancer but other cancers as well. I can’t think of better news to ring in the New Year!

Dr MacMillan specializes in Gastroenterology and Liver disease and is a member of the North Andover Board of Health. He practices at Holy Family Hospital and currently serves as President of the Massachusetts Gastroenterology Association. Dr MacMillan was recently reelected as Massachusetts Governor of the American College of Gastroenterology and is a Fellow of the College.