Fact checked byHeather Biele

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May 30, 2023
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Offering a blood test as a secondary option boosts CRC screening by nearly twofold

Fact checked byHeather Biele
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Key takeaways:

  • Offering a blood test as a secondary option in individuals who previously declined colonoscopy or FIT increased CRC screening by 7.5%.
  • There was no decrease in uptake of first-line screening options.
Perspective from Christine Lee, MD

Compared with reoffering colonoscopy and fecal immunochemical test alone, offering a blood test as a secondary option resulted in a nearly twofold increase in colorectal cancer screening in veterans who had declined first-line screening.

“We know screening prevents colorectal cancer, but participation in screening is suboptimal,” Peter S. Liang, MD, MPH, assistant professor of medicine and population health at NYU Langone Health, told Healio. “Compared to widely used screening modalities such as colonoscopy and stool-based testing, a blood test has certain advantages: It is noninvasive, can be done at point of care and does not require self-collection.”

Liang quote

He continued, “The only screening blood test currently approved by the FDA is indicated for individuals who have declined first-line tests.”

In a randomized, controlled trial published in Clinical Gastroenterology and Hepatology, Liang and colleagues assessed whether offering the septin 9 blood test, which detects the CRC biomarker methylated septin 9 DNA, as a secondary option would increase overall CRC screening uptake in people who previously had declined colonoscopy or FIT.

Researchers enrolled 359 veterans aged 50 to 75 years (75.8% aged 60-75 years, 95.5% men) at average risk for CRC who declined colonoscopy and FIT within the previous 6 months. All participants were contacted via letter and phone call to reoffer only the recommended screening options of colonoscopy or FIT (control, n = 178) or to also offer the blood test if the recommended options were declined (intervention, n = 181).

The primary outcome was completion of any CRC screening test within 6 months of outreach, while the secondary outcome was completion of a full-screening strategy of colonoscopy, negative FIT or blood test, or positive noninvasive test followed by colonoscopy.

Within 6 months of outreach, 9.6% of veterans in the control group and 17.1% in the intervention group completed any form of CRC screening, while 9% and 14.9%, respectively, completed the full-screening strategy.

“Among individuals who had previously declined screening with colonoscopy and FIT, reoffering colonoscopy and FIT with a second-line blood test option increased screening by 7.5% more than only reoffering colonoscopy and FIT,” Liang said. “There was no decrease in uptake of first-line screening tests (colonoscopy and FIT).”

Researchers also reported that of 31 veterans in the intervention group who underwent screening, 5% completed the blood test, 9.8% completed FIT and 2.2% completed colonoscopy. Conversely, among 17 individuals in the control group who underwent screening, 8.4% completed FIT and 1.1% received colonoscopy.

Overall test positivity was 18.2% for the septin 9 blood test and 8.2% for FIT.

“These results show that a blood test can improve colorectal cancer screening uptake in individuals who have previously declined colonoscopy and FIT,” Liang said. “This was a single-center VA study, so replication in other clinical environments may be needed. Whether these results will be generalizable to other blood-based CRC screening tests should also be investigated.”