Screening for Colon Cancer: Is there an alternative to a colonoscopy?

November 19, 2018

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By Kenji Kaye, M.D. and Anita R. Uppal, M.D.

Did you know that there is a cutting-edge stool based DNA test that is an effective alternative to the standard colonoscopy? It is an easy to use test that requires no special bowel preparation or dietary restrictions.  In the United States, colorectal cancer (CRC) is the second leading cause of cancer death. Each year almost 100,000 patients will be diagnosed with colon cancer according to the American Cancer Society. Fortunately, the slow course of growth of a precancerous polyp into invasive cancer allows for early detection and prevention. Screening for colorectal cancer is cost-effective and reduces death among our patients.  In the U.S. only 60% of US adults are up to date with their colorectal cancer screening. Starting at age 50 (for normal risk patients without symptoms or a family history of colon cancer), routine screening for CRC is recommended. There are multiple options for colorectal cancer screening including colonoscopy, flexible sigmoidoscopy, CT colonography, and stool blood tests.  

Many patients delay or avoid their recommended routine colon cancer screening because they do not want to go through the process of the standard colonoscopy. Usually the bowel preparation, clear liquid diet, procedural anxiety or a combination is often stated as the reason for delaying or avoiding a colonoscopy. While the standard colonoscopy remains the gold standard for colorectal cancer screening, those that would prefer to avoid a procedure are usually offered stool testing. 

  • Almost 100,000 patients will be diagnosed with colon cancer this year
  • Colonoscopy remains the standard recommended screening test
  • Stool based testing is a reasonable alternative

What about stool based testing?

Stool based testing relies on the fact that cancerous tumors and some larger polyps will bleed intermittently leading to a positive test. Traditionally, patients were sent home with a stool testing kit which tests the patient’s stool sample for signs of blood, this is also known as Fecal Immunochemical Tests (FIT).  This test works by detecting human globin which made the test much more sensitive to lower GI tract bleeding and less prone to falsely positive results. The FIT had to be repeated yearly to meet the United States Preventative Task Force recommendations and was only around 70% sensitive for detecting colorectal cancer.

What is multi-target stool DNA testing? Is it better?

In August 2014, the Food and Drug Administration (FDA) approved Cologuard, a new noninvasive stool-based colon cancer screening test. This test utilizes a multi-target approach to detect DNA and biomarkers associated with colorectal cancer and premalignant conditions. A 2014 issue of the New England Journal of Medicine reported the results of a study comparing Cologuard with traditional stool based tests and colonoscopy. Cologuard was overall around 92.3% sensitive for detecting colorectal cancer and precancerous polyps compared to the 70% sensitivity for the standard stool based tests (FIT).  

How does this test work?

A test kit is mailed to patients at home with instructions on sample collection and a prepaid return label. The completed kit can then be dropped off at any UPS location. A report is then sent to your doctor for interpretation.  If the test is negative, then the test may be repeated in three years which differs from the standard FIT testing which has to be repeated annually.  No matter which stool based testing is selected, a positive result should be further investigated with the standard colonoscopy procedure.  Your primary care physician will be able to discuss these options with you in further detail and help arrange and order the right colon cancer screening test for you. 

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This information is not intended as a substitute for professional medical care. Always follow your health care professional's instructions.

Topics: Cancer, Wellness