Total quantification of circulating microRNAs and smallRNAs in plasma and urine as prognostic biomarkers in prostate cancer.

Introduction: Circulating RNAs (cfRNAs) have emerged as promising biomarkers in liquid biopsy for prostate cancer (PCa). However, the lack of standardization in their analysis and the heterogeneity across available studies limit clinical application.

Objective: To evaluate the diagnostic and prognostic utility of the total concentration of cell-free circulating small RNA (cf-sRNA) and microRNA (cf-miRNA) in plasma and urine from PCa patients using accessible techniques, without identifying specific miRNAs.

Materials and methods: Prospective, longitudinal study including 143 men (111 with PCa and 32 healthy controls). Plasma and urine cf-sRNA and cf-miRNA levels were quantified with an Agilent 2100 Bioanalyzer. Levels were correlated with clinical features, tumor stage, and progression to metastatic castration-resistant PCa (mCRPC). A longitudinal follow-up was conducted in a metastatic subgroup.

Results: Plasma and urine levels of cf-miRNA and cf-sRNA were significantly higher in patients with advanced PCa, particularly in those who progressed to mCRPC (p < 0.05). During follow-up, a significant increase in plasma cf-miRNA was observed after treatment (p = 0.031), as well as an increase in the relative percentage of cf-miRNA in urine (p = 0.012).

Results: Plasma and urine levels of cf-miRNA and cf-sRNA were markedly higher in patients with advanced PCa, particularly in those who progressed to mCRPC (p < 0.05). Plasma cf-miRNA and the relative percentage of cf-miRNA in urine were significantly increased during post-treatment follow-up (p = 0.031 and p = 0.012, respectively).

Conclusions: Total quantification of cf-miRNA in plasma and urine is an accessible strategy with potential value as a dynamic biomarker for PCa monitoring and prognosis. Its use could complement current diagnostic tools, although further studies are required to validate its utility in clinical practice.