In the United States, colorectal cancer (CRC) is the fourth most common cancer diagnosed among adults and the second leading cause of death from cancer (Siegel, Miller, & Jemal, 2016). Screening with any one of multiple options is associated with a significant reduction in CRC incidence through the detection and removal of adenomatous polyps and other precancerous lesions and with a reduction in mortality through incidence reduction and early detection of CRC (Wolf, et al., 2018). It is recommended that adults aged 45 years and older with an average risk of CRC undergo regular screening with either a high‐sensitivity stool‐based test or a structural (visual) examination, depending on patient preference and test availability. As a part of the screening process, all positive results on noncolonoscopy screening tests should be followed up with timely colonoscopy. The options for CRC screening are: fecal immunochemical test annually; high‐sensitivity, guaiac‐based fecal occult blood test annually; multitarget stool DNA test every 3 years; colonoscopy every 10 years; computed tomography colonography every 5 years; and flexible sigmoidoscopy every 5 years. (Wolf, et. al., 2018).
Stool DNA testing has evolved into what is now a highly accurate and well-validated test for the screen detection of colorectal neoplasia. An optimized and automated multi-target stool DNA test (MT-sDNA) has achieved the same high point-sensitivities as reported for colonoscopy and significantly higher sensitivity than by fecal immunochemical blood testing for detection of early-stage cancer and advanced precancer. Thus, MT-sDNA sets a new high criterion standard for the noninvasive screen detection of colorectal neoplasia (Ahlquist, 2015).
Cologuard is a stool-based screening test for colon cancer in adults 45 years of age and older who are at average risk for colorectal cancer. Cologuard uses advanced stool DNA technology to detect the DNA and blood cells released from altered cells, and can detect both precancer and cancer, if present. In a study using multitarget stool DNA testing, the test identified 60 of 65 participants (N=9989) with cancer, including 56 of the 60 participants with screening-relevant cancers (Stage I to III), for respective sensitivities of 92.3% and 93.3% (P = .05) (Imperiale, et. al., 2014). However, false positives and false negatives may occur. In this clinical study, 13% of people without cancer received a positive result (false positive) and 8% of people with cancer received a negative result (false negative) (Imperiale, et. al., 2014).
Screening rates for colorectal cancer remain low despite strong evidence of the effectiveness of several tests and strategies. The U.S. Preventive Services Task Force states that there is no preferable screening test, as supported by several cost-effectiveness analyses (Ladabaum, Allen, Wandell, & Ramsey, 2013; Parekh, Fendrick, & Ladabaum, 2008) Offering a choice among tests may improve uptake of screening. A noninvasive test with a high single-application sensitivity for curable-stage cancer, such as Cologuard, may provide an option for people who prefer noninvasive testing.
References
Ahlquist, D. A. (2015). Multi-target stool DNA test: a new high bar for noninvasive screening. Digestive diseases and sciences, 60(3), 623-633.
Imperiale, T. F., Ransohoff, D. F., Itzkowitz, S. H., Levin, T. R., Lavin, P., Lidgard, G. P., … & Berger, B. M. (2014). Multitarget stool DNA testing for colorectal-cancer screening. New England Journal of Medicine, 370(14), 1287-1297.
Ladabaum, U., Allen, J., Wandell, M., & Ramsey, S. (2013). Colorectal cancer screening with blood-based biomarkers: cost-effectiveness of methylated septin 9 DNA versus current strategies. Cancer Epidemiology and Prevention Biomarkers, 22(9), 1567-1576.
Parekh, M., Fendrick, A. M., & Ladabaum, U. (2008). As tests evolve and costs of cancer care rise: reappraising stool‐based screening for colorectal neoplasia. Alimentary pharmacology & therapeutics, 27(8), 697-712.
Siegel, R. L., Miller, K. D., & Jemal, A. (2016). Cancer statistics, 2016. CA: a cancer journal for clinicians, 66(1), 7-30.
Wolf, A. M., Fontham, E. T., Church, T. R., Flowers, C. R., Guerra, C. E., LaMonte, S. J., … & Walter, L. C. (2018). Colorectal cancer screening for average‐risk adults: 2018 guideline update from the American Cancer Society. CA: a cancer journal for clinicians, 68(4), 250-281.
