FIT: Excellent Alternative to Colonoscopy for CRC Screening

Roxanne Nelson, BSN, RN

October 26, 2016

Colonoscopy is considered the gold standard for colorectal cancer (CRC) screening in the United States, but a new consensus statement by the US Multi-Society Task Force on Colorectal Cancer now offers strong evidence that fecal immunochemical testing (FIT) is an excellent alternative.

The consensus statement is published in Gastroenterology.

FIT is approximately 80% sensitive for detecting cancer and 20% to 30% sensitive for detecting advanced neoplasia when used as a single application test, the group notes.

Moreover, studies to date show that adherence to FIT is superior to adherence to colonoscopy and the guaiac-based fecal occult blood test (gFOBT), they add. IT also outperforms gFOBT in detecting advanced neoplasia, although endoscopic strategies appear to be superior than one-time FIT in that regard, they note.

FIT is an excellent noninvasive option for average-risk screening. Dr Douglas J. Robertson

"FIT is an excellent noninvasive option for average-risk screening," said lead author Douglas J. Robertson, MD, chief, gastroenterology, at the Veterans Affairs Medical Center, White River Junction, Vermont.

"Stool testing using conventional FOBT has been shown in large randomized controlled trial to significantly reduce death from colorectal cancer," he told Medscape Medical News. "We believe that FIT is even more effective than conventional FOBT for a number of reasons that we reviewed in our guideline."

"I think the most important message for primary care providers who are recommending the test is to be sure that their patients are committed to get colonoscopy if the FIT screen is positive," Dr Robertson added. "At the end of the day, completing the FIT is only going to help the patient if they are willing to follow through and get colonoscopy when the FIT is positive."

Earlier this year, the US Preventive Services Task Force (USPSTF) found convincing evidence that CRC substantially reduces disease-related mortality, but it stopped short of recommending one screening approach over another.

The 2016 USPSTF recommendations now include seven different screening strategies: colonoscopy, FIT for occult blood, gFOBT, sigmoidoscopy alone, sigmoidoscopy plus FIT, the FIT-DNA test, and computed tomographic colonography. All have varying levels of evidence supporting their effectiveness.

Dr Robertson commented that they focused heavily on getting screened for CRC, "rather than statements suggesting that it is better to get one test rather than another.

How Do the Tests Compare?

In the current paper, the US Multi-Society Task Force on Colorectal Cancer, which is composed of the major US gastroenterologic professional associations, examined the evidence of using FIT for CRC screening in average-risk populations and compared FIT to other commonly used screening strategies.

Compared with gFOBT, FIT has better sensitivity for detecting CRC and advanced colorectal neoplasia, but specificity is similar. The Task Force also notes that high-quality evidence shows adherence is superior for single-sample FIT as compared with the traditional three-card gFOBT.

Given this evidence, FIT is recommended over gFOBT (strong recommendation; high-quality evidence).

But it is more difficult to compare FIT with colonoscopy because there are no data yet available from head-to-head trials.

However, three ongoing randomized controlled trials are comparing colonoscopy screening with FIT, with an endpoint of CRC mortality.

One of the studies (ColonPrev) has released an interim analysis after the first round of screening, which suggests an advantage to colonoscopy. In this large study, individuals were screened with colonoscopy (n = 26,703) or biennial FIT (n = 26,599). Participation was higher in the FIT group (34.2% vs 24.6%), but there was no difference in CRC detection.

However, detection of advanced neoplasia detection was higher in the colonoscopy group (1.9% vs 0.9%), and per-protocol analysis showed a trend toward improved cancer detection in the colonoscopy group compared with the one-time FIT (odds ratio, 1.56; P = .09).

But these are only interim results, emphasizes the Task Force, and because the FIT group will continue to be screened biennially, additional cancers and adenomas will probably be detected. Thus, the long-term comparative effectiveness has yet to be determined.

Adherence to colonoscopy has been less studied, especially in the United States. A recent meta-analysis that included studies largely performed outside of the United States found that endoscopic strategies were associated with lower participation rates compared with FIT (risk ratio [RR], 0.67) but detected significantly higher rates of advanced neoplasia (RR, 3.21) (Aliment Pharmacol Ther. 2012;36:929-940).

The same analysis reported that FIT was superior to gFOBT both in adherence (RR, 1.16) and in detecting advanced lesions (RR, 2.28).

Of note, the Task Force authors point out that these trials do not generally take into account sequential testing, a commonly used approach in the United States. This strategy entails offering one test at a time, beginning with what is viewed as the most effective, and then offering a second test if the patient declines the first offer.

In addition to these comparisons, the consensus statement also offers recommendations to clinicians on implementation of FIT, such as how many times it should be performed per screening round, the time interval between rounds, and the cutoff used for defining a positive result.

Implications for Physicians

In an opinion paper published online October 25 in Annals of Internal Medicine about the new consensus statement, David S. Weinberg, MD, from the Fox Chase Cancer Center in Philadelphia, Pennsylvania, and colleagues, note, "FIT is a worthy component of any average-risk screening program," and the "use of this test should be promoted as enthusiastically as colonoscopy."

"I don't think we broke any new ground, and there are several alternatives for colon cancer screening for people at average risk," said Dr Weinberg in an interview. "And that includes FIT."

Colonoscopy and stool testing for blood are currently the only readily available screening tests offered in the United States.

Because not many options are readily available in the United States, it gives the "illusion that we are talking about one versus the other," he said. "But we're not."

For a person who is at an appropriate age for CRC screening and whose physician offers a choice of screening options, the only option that isn't appropriate is that "you're not going to do any of them," Dr Weinberg said. "But there is no obvious reason to definitively prefer one test over the other. There is pretty good data that shows that offering patients a choice — rather than being paralyzing, it is liberating."

There is no obvious reason to definitively prefer one test over the other. Dr David S. Weinberg

Many people do not want a colonoscopy for various reasons, and if they are not given any other options, some will not pursue screening at all, he pointed out.

But if a patient does want an opinion about which test is preferable, the two tests are not that simple to compare, Dr Weinberg continued. "The goal of colonoscopy is to find polyps and remove them, and thus prevent cancer from ever developing. The primary goal is to reduce the likelihood you will develop the disease, and it is better at that."

Conversely, FIT might occasionally pick up a polyp, but the real goal of the test is to detect cancer at an early and treatable stage.

"At the very basic level, the goals of both tests are to reduce mortality, but the pathways to get there are different," he explained. "So if a patient asks which test 'works better to keep me from dying,' I would say that either one is a good test."

However, implementing annual FIT screening offers challenges to primary care clinicians, Dr Weinberg and colleagues point out in their paper. There is no infrastructure to support a CRC screening program using any method, and even though the use of electronic health record is growing, "Large-scale FIT screening efforts will require efficient tracking mechanisms to ensure that the test is offered, the test kits are returned, patients with positive results are followed up with colonoscopy, and those with negative results repeat FIT in 1 year."

"FIT is ready for prime time in countries where it is a national healthcare effort, or in big organized systems like Kaiser or the VA, but for the average primary care office, it's generally not set up for that," Dr Weinberg said. "It can be done, but you're on your own."

Logistic barriers also need to be accounted for, the authors point out. For example, the US Food and Drug Administration has approved only the use of qualitative FIT reporting, which effectively predetermines the cutoff level that defines a positive test result.

But that could create problems as more sensitive tests with lower cut-points will then trigger more follow-up colonoscopies. While the cut-point for FIT that is recommended by the Task Force balances sensitivity and specificity, the authors write, it may not match what the manufacturer had chosen for some products.

Another potential problem concerns cost. As part of the Patient Protection and Affordable Care Act, CRC screening is to be offered at no cost to the patient, which in theory will reduce a major barrier to screening. But while the initial FIT is free, a follow-up colonoscopy for a positive FIT result is not.

"The test is now considered diagnostic and not part of the screening," Dr Weinberg said. "So now patients may have to pay deductibles and other costs, so it is something else to consider."

Best Test Is the One That Gets Done

Another expert agreed that the "best" test is the one the patient is willing and able to get done.

Steven Nurkin, MD, MS, assistant professor of oncology, Department of Surgical Oncology, Roswell Park Cancer Institute, Buffalo, New York, noted variations in CRC screening rates throughout the country. "Sometimes these are due to socioeconomic and racial disparities, sometimes due to individual patient factors or limited geographic healthcare resources," he told Medscape Medical News.

"When used appropriately, FIT can be performed to help identify some at-risk individuals," Dr Nurkin said. "These types of stool-based tests have the potential of reducing some of the healthcare costs and burden posed by screening tests like colonoscopies."

However, he emphasized that there is not one perfect screening test for everyone, and individuals have different risk. "Some average-risk individuals may be able to avoid more burdensome screening tests by using FIT, while other patients may require colonoscopy in conjunction," Dr Nurkin added. "Most importantly, it is clear that patients can reduce their risk by working with their physicians and tailoring their screening tests to their individual needs."

Dr Robertson is on the scientific advisory board for Medtronic; other Task Force coauthors have disclosed the following relationships: David A. Johnson is a clinical investigator for Exact Sciences and Epigenomics, David Lieberman served on scientific advisory Board for Exact Sciences, Douglas K. Rex received consulting fees from Olympus and research support from Endochoice, and Tonya Kaltenback served as consultant for Olympus America. Dr Weinberg and his coauthors and Dr Nurkin have disclosed no relevant financial relationships.

Gastroenterology. Published online October 18, 2016. Abstract

Ann Intern Med. Published online October 25, 2016. Abstract

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