Should I use Cologuard for colon cancer screening?

Cologuard is the latest screening test marketed to help detect colon cancer. This is important since colon cancer is the second most common cause of cancer-related death. It is a covenient test that can be performed on a small stool sample. In contrast, the traditional and most commonly performed examination, colonoscopy, is much more involved since it requires a direct “look” of the lining of colon. Thus, colonoscopy requires a bowel cleansing preparation that is often laborious and time-consuming.

Marketed by the Exact Sciences Corporation, Cologuard analyzes several markers for colon cancer including blood as well as amount and alteration of DNA content of cells in the stool to detect colonic neoplasia. In fact, the initial study is showing promise for this product. Cologuard was found to be superior in detecting colon cancer and advanced polyp (pre-cancerous growth) when compared to a simple test designed to detect blood in the stool.

In all fairness, Cologuard’s superiority over a simple stool blood test (costs about $5), should probably not be the only reason to rush out and get this test done. First of all, Cologuard is not covered by any major insurance at this time. This means that in all likelihood, you will have to incur about $600 in cost out of your pocket to get it done. In addition, you would actually have to collect and deliver the stool sample yourself to get the test result, a chore that most rather not take on. More importantly, Cologuard, although initially promising, has not undergone extensive clinical testing to see if it can reliably detect colon cancer. In fact, there is no data on its efficacy in detecting small polyps that are believed to grow and go on to become colon cancer. On the other hand, colonoscopy can reliably detect these small lesions and their timely removal has been shown to prevent colon cancer-related death in a large National Polyp Studies.  Furthermore, even small number of cancer missed may not be acceptable, when you are dealing with actual human lives. This is particularly the case when there is already a more accurate and reliable test that is widely available. In fact, colonoscopy for colon cancer is covered by virtually all medical insurance. Finally, if the test result for Cologuard is positive, you would have to undergo colonoscopy, anyway. In short, until its accuracy can be improved (currently only 47% for large pre-cancer and 92% for cancer) and proven to be reliable, it is probably prudent for now to stay with the proven colon cancer preventive exam: colonoscopy.