Blood-Based ctDNA Assays Show Promise but Not Yet Ready for Colorectal Cancer Screening

What happened

A systematic review of 20 studies (from 454 unique hits) evaluated blood-based circulating tumor DNA (ctDNA) assays for detecting advanced adenomas (AAs) and colorectal cancer (CRC) in asymptomatic screening populations. Comprehensive assays such as Shield, ColonSecure, and FMBT-CRC achieved the best early-stage CRC detection, with sensitivities of 71%–85% and specificities of 88%–90%. The Coloscape assay was the only one to reach sufficient AA detection, with 59% sensitivity and 92% specificity, but was tested in a small cohort. None of the reviewed assays showed sufficient sensitivity for both AA and early-stage CRC detection, and they were not superior to fecal-based immunochemical tests (FIT).

Why it matters

Current colorectal cancer screening methods have limitations in cost, accessibility, compliance, and colonoscopy capacity. Blood-based ctDNA assays could help overcome these barriers if proven effective. However, this systematic review indicates that existing assays are not yet accurate enough to serve as future screening tools, particularly for advanced adenomas. Large, prospective studies in asymptomatic populations are needed to further validate and improve these tests before they can be considered for routine screening.