Blood-based CRC screening test identifies asymptomatic, low-grade tumors
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LAS VEGAS — Multimodal circulating tumor DNA blood-based colorectal cancer screening tests may have clinically meaningful performance among patients in an average risk screening population, according to a presentation.
“Blood-based colorectal cancer screening holds potential to improve compliance with CRC screening recommendations given the ability to seamlessly integrate a blood-based test into standard of care clinical pathways,” Hee Cheol Kim, MD, of the Samsung Medical Center and Sungkyunkwan University School of Medicine in Seoul, South Korea, said during the ACG Annual Scientific Meeting presentation. “However, to contribute significantly to the CRC screening landscape, the blood-based screening test must detect CRC across multiple clinical parameters in order to prove clinically meaningful.”
To describe the performance of a multimodal circulating tumor DNA (ctDNA) blood-based CRC screening test, researchers evaluated 699 patients (43% women; median age, 63 years) newly diagnosed with CRC. Prior to surgical resection, patients provided a blood sample from which the panel analyzed isolated plasma to identify cancer-related genomic alterations and epigenomic modifications. The panel provided an output of either “ctDNA detected” or “ctDNA not detected.”
According to results, the overall sensitivity was 96% which ranged from 88% to 98% across cancer stage, presentation, primary tumor location, histology, grade, degree of tumor invasion and microsatellite instability status. Among 138 patients with low-grade CRC, sensitivity was 93%. Further, sensitivity was 90% among 142 patients who were asymptomatic at presentation and 97% among 192 patients with low-grade disease with symptomatic presentation. Kim noted a 94% specificity among age-matched cancer-free controls.
“This multimodal ctDNA CRC screening test has clinically meaningful sensitivity across multiple clinical parameters, most notably in those with early-stage asymptomatic low-grade tumors,” Kim concluded. “The data suggests that this test may have clinically meaningful performance in an average risk screening population presenting with varying cancer stages and tumor histologic features. Future studies aim to validate this test in a screening-relevant population.”
Perspective
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Mohamad Mouchli, MD
Blood-based screening tests are appealing for many patients undergoing colorectal cancer screening. This interesting study assessed the role of multimodal ctDNA blood-based CRC screening tests as a new innovation to screen average risk individuals for colorectal cancer. Blood samples obtained from patients with recently diagnosed colon cancer before surgical resection and test sensitivity were compared between symptomatic and asymptomatic patients. The test was found to have high sensitivity and specificity that is comparable to screening tests recommended by the U.S. Preventive Service Task Force (USPSTF).
Despite the clear evidence that colorectal cancer screening reduces cancer incidence and mortality, participation rates in screening programs remains low. Some barriers limiting screening participation are embarrassment, fear of procedures, lack of knowledge, limited access to care and cultural differences. Current blood-based screening tests are not effective in screening and were not recommended by the USPSTF. This new innovation may have a promising role in screening average risk individuals who are resistant to take one of the available screening tests. The test still needs to be validated in a prospective way and compared to available tests. In the meantime, the best test remains the one that is “being done.”
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Kim HC, A, et al. Abstract: Multimodal circulating tumor DNA (ctDNA) blood-based CRC screening test demonstrates clinically meaningful sensitivity across multiple clinical parameters. Presented at: ACG Annual Scientific Meeting; Oct. 22-27, 2021; Las Vegas (hybrid meeting).
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