Q&A: Screening-based test for colorectal cancer is ‘only as good as its uptake’
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Guidelines that recommend stool-based screening for colorectal cancer should emphasize strict adherence and offer screening colonoscopy as an alternative option, researchers reported in Gastroenterology.
“The reasoning for undertaking this investigation hinged on the decades-long belief that CRC was preceded by polyps; this was proven by our National Polyp Study, which demonstrated prevention of CRC by colonoscopic polypectomy. Screening colonoscopy was then incorporated into guidelines,” co-principal study investigators Sidney J. Winawer, MD, and Ann G. Zauber, PhD, of Memorial Sloan Kettering Cancer Center in New York City, told Healio. “However, studies needed to be initiated to observe its adherence and effectiveness.”
They noted: “We decided to design two companion studies, one that would address adherence and pathology outcomes to screening colonoscopy and sequential high sensitivity fecal occult blood testing (the National Colonoscopy Study [NCS]), and a second, which would address the long-term effectiveness of the two tests based on the NCS data.”
In a randomized clinical trial, researchers enrolled 3,523 participants aged 40 to 69 years who underwent either single screening colonoscopy (n = 1,761) or four to seven sequential rounds of high sensitivity fecal occult blood testing (HSgFOBT; n = 1,762).
Outcomes of interest included initial adherence, follow-up colonoscopy for positive HSgFOBT tests, crossover to colonoscopy and detection of advanced neoplasia or large serrated lesions (AND-SER).
According to results, adherence for colonoscopy was 83.6% vs. 73.1% for HSgFOBT after one round (RR = 1.14; 95% CI, 1.1-1.19) and 38.3% over four sequential rounds (RR = 2.19; 95% CI, 2.05-2.33). Adherence increased to 88.5% in the colonoscopy arm and 84.7% in the HSgFOBT arm (RR = 1.04; 95% CI, 1.02-1.07) over the course of the study. Nearly one-quarter (24.7%) of participants crossed over to screening colonoscopy after the first four rounds.
Researchers detected AND-SER among 8.2% of colonoscopy-adherent participants and 3.3% of HSgFOBT- adherent participants, compared with 0.6% among participants who were not adherent to HSgFOBT in the first four rounds.
In a Healio interview, Winawer and Zauber broke down the study findings and how they might inform patient care going forward.
What were the key takeaways?
Winawer and Zauber: There are several key takeaways. The poor screening colonoscopy adherence in the European studies, and their subsequent negative media, does not represent U.S. expectations and practice. A high adherent single screening colonoscopy may be a more effective screening option than HSgFOBT, which has low programmatic adherence.
When HSgFOBT screening is offered, it is desirable to have screening colonoscopy available as an alternative option. Guidelines need to more clearly emphasize the requirement for programmatic adherence when FOBT testing is offered.
What additional research is needed?
Winawer and Zauber: The long-term effectiveness of screening colonoscopy compared to a program of stool-based tests (HSgFOBT, FIT, DNA/FIT) needs to be determined. There are several randomized controlled trials in progress. These studies are mainly European, with one in the U.S. in a majority all-male veteran population.
In addition, the second part of our study is a predictive microsimulation model of long-term effectiveness of screening colonoscopy compared to HSgFOBT based on the NCS data just reported. This has been completed and is being prepared for submission.
How might these results inform patient care going forward?
Winawer and Zauber: In the context of a U.S.-based patient care setting, when offering CRC screening, colonoscopy is the test that will most likely be accepted. Stool-based testing should be offered as an alternative but needs to be completed every year over at least 3 years to be effective.
Structured sequential adherence to a stool-based test must also be emphasized among clinicians in order to receive maximum benefit in the offered test. A screening-based test is as only good as its uptake. Finally, it should be emphasized that any screening test is better than none, and the best test is the one that gets done and done well.
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