• The fecal immunochemical test (FIT) and multitarget stool DNA (mt-sDNA) test are two of the most commonly used noninvasive screening tests for colorectal cancer.
• A new study analyzing data from a national insurer’s claims database suggests that FIT was more cost-effective than the mt-sDNA test but did not differ in patient outcomes.
• These results could inform decision-making by clinicians when suggesting noninvasive colorectal screening tests to patients.

A new study published online in advance in the Journal of the American College of Surgeons suggests that completely transitioning to the fecal immunochemical test (FIT) for noninvasive colorectal cancer screening instead of multitarget stool DNA (mt-sDNA) tests could result in significant cost savings without compromising the quality of care.

Study co-author Dr. Pavan Rao, a general surgery resident at Allegheny Health Network in Pennsylvania says that:

“Despite national guidelines suggesting that FIT be used as the primary noninvasive screening modality, we found that on review of our insurer’s claims data, a significant proportion of patients still receive a more expensive alternative test. There are substantial cost savings not only to our patients but to our health system by promoting the appropriate use of noninvasive testing. There was no difference in the clinical stage at the time of diagnosis between the two tests, which again demonstrates the clinical equipoise maintained by switching to FIT.”

“I think a colorectal surgeon or any specialist who sees appropriate patients for colorectal cancer screening can use this data to provide recommendations of alternative screening tests to patients who primarily do not want to undergo colonoscopy,” adds Dr. Rao.

The study was recently presented at the Scientific Forum of the American College of Surgeons (ACS) Clinical Congress 2022.

Colonoscopies vs noninvasive screening

Colorectal cancer is the third most diagnosed cancer and the second leading cause of cancer deaths worldwide. Regular colorectal cancer screening can reduce the risk of colorectal cancer incidence and mortality.

Most colorectal cancers develop as polyps, which are noncancerous outgrowths of the inner lining of the rectum or colon. Colorectal cancer screening allows for the early detection and removal of these precancerous polyps.

Despite the recent controversy around the effectiveness of colonoscopy, it is generally regarded as one of the most effective methods for the screening and detection of colorectal cancers due to its high sensitivity.

During this procedure, a healthcare provider uses a colonoscope, a long, flexible tube with a camera and a light at one end, to examine the inner lining of the rectum and colon for polyps or other abnormalities. Moreover, colonoscopy also allows for the removal of small polyps during the procedure.

However, factors such as embarrassment and the need for bowel preparation — involving the use of laxatives — and dietary restrictions before the procedure tend to deter individuals from undergoing a colonoscopy. In addition, colonoscopy is associated with a small risk of bleeding and perforation of the colon.

The sometimes prohibitive costs of a colonoscopy can also put people off from agreeing to undergo this procedure.

Individuals who are unwilling to undergo a colonoscopy do have the option of taking a noninvasive screening test. Stool tests such as the fecal immunochemical test (FIT) and the multitarget stool DNA test (mt-sDNA) are some of the most common non-invasive colorectal cancer screening tests.

Polyps or small cancers in the colon and rectum can result in minor bleeding that cannot be detected visually. The FIT uses antibodies to detect small traces of blood in stool samples.

The development of cancer is associated with DNA alterations and changes in gene expression patterns in tumor cells. The mt-sDNA test detects markers of altered DNA in cells lining the colon and rectum, which are shed daily in the stool.

The FDA-approved mt-sDNA test also contains a FIT component to detect blood in the stool sample. Both the FIT and mt-sDNA test do not entail dietary restrictions or bowel preparation.

Benefits and shortcomings

Each screening procedure has its benefits and shortcomings. Dr. Payton Yau, a microbiologist at Scotland’s Rural College, United Kingdom, told Medical News Today: “FIT is cheap and cost-effective; however, the tumor may not bleed and thus we may get false negative results. mt-sDNA is a patented product targeting a set of targeting genes plus hemoglobin, which means it is relatively expensive as the ‘extra’ lab work required.”

Similarly, Dr. Samir Gupta, a gastroenterologist at the University of California San Diego, said: “The mt-sDNA test has a higher rate of false positives, but also is more likely to pick up large polyps than FIT. [The mt-sDNA test is also] somewhat more complicated to do than FIT alone, because there are more steps involved.”

A positive result in the FIT or the mt-sDNA test is followed by a colonoscopy to confirm the presence of pre-cancerous or cancerous tissue.

Cost-effectiveness of different stool tests

The recent study used a national insurer’s claims database to compare the cost-effectiveness of FIT and the mt-sDNA test. Among the 117,519 individuals who underwent non-invasive colorectal cancer screening in 2019, around 38.7% of individuals were screened using the FIT, whereas 39.2% were screened with the mt-sDNA test.

After taking into account the cost of the tests, the number of patients using each test, and the downstream costs due to inaccurate results, the researchers estimated that costs associated with FIT amounted to $1.1 million in 2019, whereas the mt-sDNA test-associated costs totaled about $5.6 million.

Moreover, if all individuals who underwent noninvasive screening were to be screened using FIT alone, it would have resulted in savings of $3.9 million per year.

Comparing the clinical impact of these tests, the researchers found that a similar proportion of individuals screened using the FIT (59.5%) and the mt-sDNA test (63.2%) later presented with early-stage colorectal cancer after undergoing follow-up tests.

These results suggest that FIT is more cost-effective than the mt-sDNA test, without necessarily impacting the quality of clinical care.

Implications

The study authors claim that these results could inform decision-making by clinicians. Consistent with this, Dr. Folasade May, an associate professor of medicine at UCLA, commented: “FIT is the 2nd most common colorectal cancer screening modality in the US after screening colonoscopy. FIT-DNA is a newer stool-based screening option. Although it has grown in popularity, it has always been less commonly used than FIT.”

“This is because it is newer, is only recently covered by many insurers, and may require out-of-pocket costs for many individuals,” she added.

“I do think that the study results support a shift from colonoscopy screening to stool-based screening tests. The [United States Preventive Services Task Force] recommends seven strategies for colorectal cancer screening. Patients should consider the pros and cons of all seven of these strategies and pick the test that is best for them. Some patients will pick these stool-based tests — FIT and FIT-DNA — because they are noninvasive, cheap, and can be done in the comfort of their own home,” noted Dr. May.

Dr. Guido van Hal, a medical sociologist at the University of Antwerp, Belgium, however, pointed out that multiple studies have shown that the mt-sDNA test has higher sensitivity (low rate of false negatives), but lower specificity (higher rate of false positives) than FIT.

Dr. van Hal said:

“We think the current evidence favors FIT over mt-sDNA in terms of cost-effectiveness, but more materials — other simulation studies on the cost-effectiveness of FIT vs. mt-sDNA, and studies on the impact of FIT in actual screening programs — are needed for a good argumentation. We also think that mt-sDNA or other DNA tests to detect specific biomarkers have more potential — e.g. due to cost-effectiveness — to be used as an in-between test after a positive FIT, instead of a first-step screening test in a nationwide screening program.”

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