Earlier this year, the U.S. Preventive Services Task Force (USPSTF) updated the recommendations for colorectal cancer screening. But European clinicians claim that USPSTF recommendations lack strength and quality of evidence.
Their opinion was published in the Annals of Internal Medicine in a study titled “America, We Are Confused: The Updated U.S. Preventive Services Task Force Recommendation on Colorectal Cancer Screening.”
When recommendations are made for a certain screening method, those drafting the guidelines should inform readers about the degree of trustworthiness behind their recommendations. If a screening technique has been proven effective in randomized clinical trials, it should be recommended more strongly than other techniques that have been addressed only in modeling studies.
“If high-quality randomized trials exist for a screening strategy, there is a clear expectation for strong recommendations,” Michael Bretthauer, MD, PhD, from the KG Jebsen Center for Colorectal Cancer at the University of Oslo, Norway, and colleagues wrote.
“On the other hand, for screening strategies without evidence from high-quality randomized trials, recommendations should be issued with greater caution and should include an explicit justification of why the balance of benefits and harms was considered to be positive,” he added.
Although only two of the currently used screening methods have been validated in high-quality randomized trials, the USPSTF graded all screening tests as a single test. These tests, as Bretthauer and colleagues note, differ significantly in their mode of action, invasiveness, and quality of evidence for effectiveness.
“Contrary to the principles of evidence-based medicine, the guidelines provided equally strong recommendations for tests with very different quality of evidence for benefits and harms,” the researchers wrote.
Guidelines from the European Union recommend that screening tests are introduced in routine healthcare only after their effectiveness has been proven in randomized trials. As a result, only sigmoidoscopy and guaiac-based FOBT (fecal occult blood testing, or FIT, the modern version) are currently recommended for routine use in Europe.
The USPSTF, however, recommends five other tests — colonoscopy, FIT (not the same test above), computed tomography colonography, FIT DNA testing, and a combination of sigmoidoscopy and annual FIT — that have not been tested in randomized clinical trials.
And although the European researchers note that the strong recommendations for these five tests can be justifiable, the USPSTF did not provide an explanation for their recommendations.
In addition, although the combination of sigmoidoscopy and FIT has been tested in a randomized clinical trial, the recommendations do not correspond with what the trial showed. First, no trials have tested sigmoidoscopy plus annual FIT, as recommended by the USPSTF. Second, the trial demonstrated that the mortality from colorectal cancer did not differ in the group of patients receiving sigmoidoscopy alone compared to those receiving sigmoidoscopy plus FIT. And although the combination arm showed a trend toward better effectiveness, sigmoidoscopy alone showed a trend toward improved cancer incidence.
“To generate high-quality evidence for effectiveness of new screening strategies, we consider the integration of high-quality clinical trials into ongoing screening programs as the only viable solution,” Bretthauer and colleagues wrote.
“We hope these trials will give some of the answers we lack to provide individuals, decision makers, and healthcare workers with the evidence base needed for informed decision making.”
