Diagnostic utility of urinary cell-free DNA in non-urothelial cancer: a systematic review, meta-analysis, & network meta-analysis.

[PURPOSE] Urinary cell-free DNA (ucfDNA) offers a noninvasive approach for cancer detection, but its diagnostic utility in non-urothelial cancers remains unclear. We systematically evaluated the diagnostic and prognostic value of ucfDNA for these cancers and compared its performance with other liquid biopsies through network meta-analysis.

[EXPERIMENTAL DESIGN] We conducted a systematic search of PubMed, Cochrane Library, and other databases for studies from 2010 to 2025 evaluating ucfDNA for diagnosing or predicting prognosis in non-urothelial cancers. Primary outcomes were pooled diagnostic sensitivity and specificity; secondary outcomes included prognostic hazard ratios (HRs). Study quality was assessed using QUADAS-2, and Bayesian hierarchical models were employed for robust estimates.

[RESULTS] Twenty-eight studies involving 4,423 participants were included. Overall pooled sensitivity was 0.80 (95 % CI, 0.75-0.85) and specificity was 0.96 (95 % CI, 0.88-0.98), with significant heterogeneity (I > 82 %). Subgroup analysis of studies targeting short amplicons (<70 bp) showed improved specificity of 0.98 and substantially reduced heterogeneity (I = 0 % for specificity). Limited post-treatment ucfDNA reduction was a strong predictor of poor prognosis (pooled HR, 2.76; 95 % CI, 1.94-3.91). Exploratory network meta-analysis in non-small cell lung cancer comparing urine, plasma, and sputum showed overlapping confidence intervals, though the limited available data and wide confidence intervals preclude definitive conclusions regarding comparative performance. Mutation-based assays demonstrated significantly higher specificity than methylation-based approaches (99 % vs. 72 %, P < 0.01).

[CONCLUSIONS] ucfDNA demonstrates high diagnostic specificity for non-urothelial cancers and provides significant prognostic information. Optimizing assays for ultrashort DNA fragments is critical for enhancing performance and reducing variability. These findings support the potential utility of ucfDNA, particularly as a complementary tool alongside established liquid biopsies like plasma cfDNA, to enhance non-invasive cancer diagnosis and monitoring. Its role as a standalone diagnostic requires further validation, and method standardization remains essential for broad implementation.

[CLINICAL TRIAL REGISTRATION] PROSPERO CRD420251073863.