The recent Nordic-European Initiative on Colorectal Cancer (NordICC) trial – a randomized study on the effects of colonoscopy screening for risk of colorectal cancer (CRC) and related death – offers some illuminating results.
The study confirms colonoscopy screening as an effective means of detecting cancer early. For patients screened, the risk of death from CRC was reduced by 50 percent (1). However, the study also showed that only 42 percent of patients referred for a colonoscopy actually went through with the screening.
The NordICC trial sheds new light on an unfortunate but familiar reality – only two in three eligible individuals in the US are being screened for CRC in line with medical guidelines. The study points to stool-based testing as an alternative, but recent research published in The Lancet shows a compliance rate of only 55 percent for stool-based screening (2).
The National Colorectal Cancer Roundtable has set a goal to screen 80 percent of eligible US individuals. But there are challenges associated with currently available screening methods – they can be inconvenient and difficult to access and there is discomfort with stool-based tests. Developing accessible testing to screen for colorectal cancer is therefore crucial. And I believe blood testing is one option that can overcome current barriers.
To date, most of the criticism of blood-based screening has focused on its sensitivity – or lack thereof. And I agree that sensitivity is crucial; delayed detection of cancer at this early stage can lead to sometimes debilitating chemotherapy side effects and higher risk of death. High sensitivity in screening tests also helps minimize patient anxiety about false negative results. In recent studies, blood-based CRC screening tests have demonstrated sensitivity above 80 percent with specificity of 90 percent (3). These figures are consistent with other screening methods. The high specificity (low false positive rate) can help minimize unnecessary diagnostic procedures, which preserves limited lab and healthcare resources and optimizes patient care and safety.
In terms of improving patient outcomes and public health, the best screening test is the one that the patient actually completes. Blood-based testing has been shown to significantly enhance adherence to CRC screening in a real-world setting. Looking at our internal data, of the initial 8,000 individuals whose physician ordered one blood-based CRC screening test during a routine visit, 90 percent completed the test.
If nothing else, the NordICC trial demonstrates that we need more alternatives to colonoscopy if we want to screen average-risk populations for CRC effectively. Current screening rates lag well below the US target, in part because the available methods are perceived as unpleasant, time-consuming, and difficult to complete. Blood tests, however, offer a convenient and effective alternative for patients – with the potential to increase screening rates and save more lives.
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References
- M Bretthauer et al., “Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death,” N Engl J Med, 387, 1547 (2022). PMID: 36214590.
- A Forsberg et al., “Once-only colonoscopy or two rounds of faecal immunochemical testing 2 years apart for colorectal cancer screening (SCREESCO): preliminary report of a randomised controlled trial,” Lancet Gastroenterol Hepatol, 6, 513 (2022). PMID: 35298893.
- Guardant Health, “Guardant Health announces positive results from pivotal ECLIPSE study evaluating a blood test for the detection of colorectal cancer” (2022). Available at: http://bit.ly/3zVPVeQ.
