The cost of the MT-sDNA test has been a concern voiced by many organizations and researchers. An analysis of the cost-effectiveness of Cologuard at intervals of 1, 3, or 5 years compared with no screening at all was performed.18 The cost-effectiveness ratio of the MT-sDNA test with these screening intervals concluded that all intervals were cost-effective relative to a conservative willingness-to-pay threshold of $25,000 per quality-adjusted life-year. The Cologuard cost-effectiveness ratio was found to be comparable to other common cancer screening tests such as an annual Papanicolaou smear and annual mammogram. Another analysis determined the FIT and colonoscopy to be more effective and less costly than the MT-sDNA test when participation rates were equal for all strategies.19 It was determined that the participation rate of using the MT-sDNA test would need to be substantially higher to be considered a cost-effective choice. 

Similar to the MT-sDNA test, the FIT is an evidence-based, noninvasive CRC screening test. However, it has been on the market for a longer period of time than the MT-sDNA test. The FIT has a high level of accuracy, high specificity, and moderately high sensitivity for detection of CRC.5,7,11,12 The sensitivity of the FIT in detecting proximal and distal adenomas was similar.7 In general, these studies support the use of FIT in detecting noninvasive, nonadvanced CRC, but there are concerns with the FIT’s ability to detect premalignant lesions.11

To increase the FIT’s detection of premalignant lesions (SSA/Ps), a strategy of multiple-round testing has been suggested.11 It also has been proposed that repeating FITs would likewise increase the diagnostic yield of CRC, and that completing 3 FITs over time instead of 1 would be beneficial.7,11 However, many researchers are concerned with the idea of multiple-round testing, noting that this strategy may detract from the test’s credibility, lead to increased cost, and challenge patient compliance because of the need for repeat collection.

A challenge exists for providers desiring to recommend the use of FIT in practice because a variety of brands is available. Studies comparing FIT and colonoscopy are complicated by this because of the different brands all having varying Hgb thresholds for what constitutes a positive test. The different cutoff values for Hgb can lead to disparate results for both sensitivity and specificity.12 This was demonstrated in a study in which 4 different brands of the FIT were used.10 Another study compared 8 different brands of the FIT for sensitivity and specificity and found that only two-thirds of the tests performed acceptably.8 To further complicate this matter, information on proficiency testing programs is not available to the public, so it is difficult to determine whether the FIT being used is actually performing as the manufacturer claims it will in the hands of the consumer. There have been no head-to-head comparisons between the different commercial FITs, which may be useful to determine which 1 performs best. 

Another significant area of concern is the use of qualitative vs quantitative FITs, which vary significantly in design and testing. Qualitative FIT products often use a dipstick technology, whereas quantitative FITs are measured by technically precise, automated instruments. Advantages of the qualitative FIT include convenience, low cost, and rapid turnaround.12 However, the quality control of the qualitative FIT is a concern. The quantitative FIT allows for the selection of a test with a specific Hgb threshold that will maximize the detection of CRC and minimize false-positive results.20 Future studies are needed to determine what the Hgb threshold should be and how to standardize these tests. 

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Conclusion

Can providers feel confident in recommending the FIT or the MT-sDNA test for CRC screening in patients of average risk between the ages of 50 and 75 years who do not want to have a colonoscopy? The MT-sDNA test has a high sensitivity but low specificity, whereas the FIT has a low sensitivity and high specificity. The MT-sDNA test’s low specificity raises concerns of false-positives and unnecessary testing; the FIT’s low sensitivity raises concerns about what it can detect. Ultimately, more studies are needed on the MT-sDNA test and FIT. Even though they are both approved tests for CRC screening, they each have pros and cons that need to be considered.

This literature review was limited because of the few published studies comparing the MT-sDNA test with the gold-standard colonoscopy. Two articles reviewed refer to a large, average-risk screening study currently underway to validate findings of the MT-sDNA test.14,17 Hopefully, this study can show the current specificity of the test and how to increase it. It is possible with more research that the MT-sDNA test may earn improved coverage by insurance companies and become a more cost-effective test for CRC screening. One of the articles reviewed reports that large, randomized trials are also under way to compare the FIT with colonoscopy as a CRC screening program, but results will not be available for some time.20 Additional research for both tests is needed to optimize completion of the initial test and follow-up colonoscopy when a positive result is received. These studies could help find ways to increase the number of patients following through with CRC screening recommendation. 

Related Articles

One-third of average-risk individuals in the United States have never had colorectal cancer screening completed after a recommendation from a healthcare provider.3 Offering sound choices in CRC screening strategies should be the goal of every provider. Healthcare providers should focus on maximizing the total number of patients that participate in CRC screening because it will have the largest effect on preventing deaths related to colorectal cancer. Despite the need for additional research, the FIT and the MT-sDNA test are both evidence-based tests that should be considered for patients when presenting options for CRC screening when a colonoscopy is unable to be performed.

Amanda N. Strain, MSN, CCRN, FNP-C, is a family nurse practitioner at Kendrick Family Medicine in Mooresville, Ind.; Charlotte C. Waling, MSN, FNP-C, is a nurse practitioner at St. Vincent Ambulatory Care Crawfordsville, Primary Care Department, Crawfordsville, Ind.; and Felicia D. Stewart, DNP, NP-C, RN-BC, is an assistant professor, Department of Advanced Practice Nursing, Indiana State University, and family nurse practitioner at Wellness for Life in Terre Haute, Ind.

References

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