Noninvasive colorectal cancer screening
FIT and MT-sDNA are CRC screening alternatives when a colonoscopy cannot be performed.
The second leading cause of cancer-related deaths in the United States is colorectal cancer (CRC).1 The US Preventive Services Task Force2 anticipated that 134,000 people would be diagnosed with, and 49,000 people would die from, CRC in 2016 alone. CRC has a 90% 5-year survival rate when it is diagnosed early.1 Unfortunately, only 40% of people have CRC identified at an early, treatable stage.1
There is compelling evidence that CRC screening in asymptomatic adults from 50 to 75 years of age significantly reduces the mortality associated with CRC. A colonoscopy remains the “gold standard” in colorectal screening tests, but as many as 1 in 3 Americans, or more than 20 million people, do not adhere to their healthcare provider's recommendation to have a screening colonoscopy.3
For example, if someone of average risk between the ages of 50 and 75 years is resistant to having a colonoscopy, are there other viable options providers can offer patients? Two stool tests to consider for colorectal screening include the fecal immunochemical test (FIT) and the multitarget stool deoxyribonucleic acid (MT-sDNA) test. The American Cancer Society4 reports that patients find these tests more attractive than a colonoscopy because of the limited preparation required and the convenience of completing the test at home. The FIT requires a small sample of stool in a test tube or card and uses antibodies to detect hemoglobin (Hgb) in the stool.4 The MT-sDNA test requires a full stool sample and analyzes the stool specimen for DNA markers that signal neoplastic changes.4 Both test samples must be sent to a laboratory for testing.
The purpose of this literature review is to explore the published evidence regarding the efficacy of 2 CRC screening stool tests: the FIT and the MT-sDNA test. This information will assist clinicians in determining whether these tests can be considered in lieu of a screening colonoscopy when patients decline the gold standard recommendation. This topic deserves attention because of the discrepancy between the number of people who are given the recommendation for CRC screening and the number who actually follow through with it. If the newer, noninvasive tests are effective in screening for CRC, then this may offer more choices and result in increased numbers of patients obtaining CRC screening.
The Cochrane Library was the initial database that was searched because of the clinical nature of the topic. We searched the database for “colon cancer screening” in the title, abstract, and keyword fields, with no limitation for publishing year. Six items resulted, but they were not pertinent to the focus of this review. Similar searches were conducted for the following keywords both alone and in combination: “colorectal cancer screening,” “colon cancer,” “fecal immunochemical,” “multitarget stool,” and “stool sample test.” Four reviews resulted for “fecal immunochemical.” One systematic review focused on the FIT alone and was saved for this literature review, but the 3 other results compared the FIT with guaiac-based fecal occult blood tests and were eliminated. Fecal occult blood tests are outside the focus of this literature review. Three clinical trial reports resulted for “multitarget stool,” but no systematic reviews. Ultimately, no systematic review was found in the Cochrane Library for the MT-sDNA test or for comparison between the FIT and the MT-sDNA test.
Literature searches were then conducted for studies on the topic of CRC detection using either the FIT or the MT-sDNA test. The EBSCOhost database was used to search Academic Search Complete, CINAHL, and MEDLINE for articles published from 2012 to 2017. Searches used the following key terms and combinations of terms: “colorectal cancer screening,” “DNA stool,” “stool DNA test,” “multitarget stool,” “fecal immunochemical test,” “average risk,” “systematic review,” and “cancer.” Initial searches were conducted without limiters. In cases in which there were thousands of results, records were filtered to include reviews and/or clinical studies. Once the search yielded fewer than 150 articles, titles and abstracts were reviewed to further narrow down the results. Studies that met all inclusion criteria were set aside for further review.
The inclusion criteria applied to the searches were that the studies examined CRC detection rates of either the FIT or the MT-sDNA test, the articles were published in 2012 or after, and the studies used quantitative measures to describe their findings. Studies were not excluded because they incorporated additional qualitative data on study variables such as “ease of use.” Studies of single-biomarker stool DNA tests (brand names ColoVantage and ColoSure) were excluded because this review pertains to the MT-sDNA test, which is a multiple-biomarker test (brand name Cologuard). Although this review focuses on persons at average risk for CRC, studies were not excluded for providing data for persons at higher risk resulting from familial risk or past history of CRC. This review also focuses on persons between the ages of 50 and 75 years, but studies were not excluded for having narrower age ranges or being outside this range. The youngest individuals included in the studies were aged 40 years. Abstracts of the remaining articles were checked to ensure they matched the topic and were study reports, not opinion articles. A total of 13 published articles remained at the end of the literature search process for inclusion in this literature review.