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Noninvasive Cancer Screening—Will We Ever Get It Right?

By: Frances Sousonis, Candidate c/o 2017

Unfortunately, cancer is a disease about which many are able to share stories. All too often, beloved persons are diagnosed with cancer, or, more regrettably, loses their battle with the beast. Colon cancer is the third most common cancer in the United States and around 150,000 people each year are affected by it .1 Because early diagnosis makes an enormous difference in patient outcomes, many researchers work hard to find a detection tool that is more convenient, more accurate, and thus more appealing than the current procedures, such as colonoscopies. There are other on-going researches to find ways to handle different types of cancer. Cancer will continue to be treated with urgency, but new developments in the medical field may help strip the condition of its edge.

A new noninvasive test has been found to be effective in detecting cancer. While the test is originally designed for colon cancer, it may also be able to detect abnormal tissue growth associated with various other cancers.2 This newly developed screening test called Cologuard seeks mutations in DNA through the patients’ stool samples. 2 It may seem odd to the public to mail in these samples, but anything that could help discover cancer before it metastasizes is worth a shot. In essence, if proven to be superior, the stool sample testing will replace colonoscopy, which is the gold-standard for those at risk of colon cancer.

Currently, there are researches for methods other than Cologuard for cancer. These may involve diagnosis or treatment. For instance, Swedish scientists found that cardiac glycosides may play a role in killing cancer cells; however, the concentration of the drug in patient plasma would be at a rate that is unattainable.3 Other areas such as genetics, vitamin supplements, and immunotherapy are also being investigated.3 The cause for colon cancer is partly genetics, but certain vitamins and medications such as calcium, vitamin D, folic acid, and aspirin can help lower the likelihood of developing colon cancer.4 In immunotherapy, researchers are trying to develop vaccines that will either kill the cancer cells or prevent recurrence once the patient is in remission. The patient would have their own dendritic cells (cells of the immune system) altered in vitro and re-instilled to better fight off the cancer cells.4 Currently all of these options are only available in clinical trials, not in practice.

On the other hand, the newly studied non-invasive procedure, Cologuard, may be available to the public soon if further studies consistently support its benefits, but this seems unlikely. Questions are raised about whether the test is superior to the existing noninvasive procedures. Exact Sciences Corporation , the company that invented Cologuard, states that the test is about 92% accurate in detecting cancer.2 The Cologuard test is no match for colonoscopy, because the latter can remove polyps—early indications of colon cancer—at the time of the procedure, thus possibly preventing cancer.2

In addition, Cologuard would most likely be marketed for several hundred dollars whereas the current noninvasive test that detects blood in stool samples—Fecal Immunochemical testing (FIT) — goes for about $25.2 Dr. Deborah A. Fisher, who is unaffiliated with the testing of Cologuard, is a professor of medicine at Duke University, and is the consultant to Epigenomics—a company developing a test that could compete with Cologuard—says that Cologuard is no “holy grail.”2 Cologuard detects mutations in the DNA obtained from the stool sample, whereas other stool tests search for the presence of occult blood, or blood that cannot be seen with naked eyes, in the stool. Testing for blood in stool is much simpler and cheaper as opposed to testing the DNA obtained from stool, causing this drastic monetary difference. 2 The test uses the DNA sloughed off and disintegrated from intestine linings, which mostly consist of gut bacteria. Testing DNA this way is very challenging. Dr. David A. Ahlquist, a professor at the Mayo Clinic who helped develop the Cologuard test, says that “only 0.01 percent is the person’s own DNA, and of that, only a tiny fraction would be from cancerous cells.”2 In essence, the benefits of the new procedure don’t seem to be adequate for Cologuard to be approved by the FDA.

Despite the doubts, the Exact Sciences Corporation is persistent with its plan. The inventors say that because it requires less time to take a stool sample, more people would be willing to get screened. Actually proving the public’s inclination would be difficult, putting the company’s claims at a disadvantage. While the intent for Cologuard is admirable, more research is still needed.

The fight against cancer continues on. One can hope that with research, soon cancer will not be as devastating a disease as it is now.


  1. Cardiac drugs may fight colon cancer. US Pharmacist, A Jobson Publication Web site. Published January 20, 2010. Accessed May 3, 2013.
  2. Pollack Andrew. Noninvasice cancer test is effective, study finds. New York Times Web site. Published April 18, 2013. Accessed May 3, 2013.
  3. Felth J, Rickardson L, Rosen J, et al. Cytotoxic effects of cardiac glycosides in colon cancer cells, alone and in combinations with standard chemotherapeutic drugs. Journal of Natural Products. 2009;72(11):1969-1974. Accessed May 30, 2013.
  4. What’s new in colorectal cancer research and treatment? American Cancer Society Web site. Updated January 17, 2013. Accessed May 30, 2013.
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