Discordant Dynamics Between Absolute ctDNA and Tumor Fraction During Treatment Monitoring in Metastatic Colorectal Cancer: Evidence of a Dilution Phenomenon
Blood tumor DNA monitoring shows a 'dilution effect' where absolute DNA levels and tumor burden can diverge, requiring both metrics for accurate clinical interpretation.
This study documents a 'dilution phenomenon' in ctDNA monitoring for metastatic colorectal cancer, where tumor fraction can decrease despite rising absolute ctDNA — a finding with important implications for clinical interpretation of ctDNA-based monitoring panels that report only tumor fraction. Clinicians relying solely on tumor fraction may underestimate tumor progression in these cases, suggesting absolute ctDNA quantification should be reported alongside tumor fraction.
What the study was
- Study design
- Retrospective longitudinal study
- Population
- Metastatic colorectal cancer patients on systemic therapy with serial ctDNA monitoring
- Sample size
- 55
- Category
- Diagnostics
- Maturity
- Exploratory
- Journal
- Clinical Colorectal Cancer
Why it surfaced
Clinically actionable insight for ctDNA monitoring interpretation in mCRC; small study but raises important methodological caution for ctDNA panels reporting only tumor fraction.
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