Table 1.

Conceptual comparison of exosomal miRNAs and circulating tumor DNA (ctDNA) in prostate cancer recurrence detection.

Feature	Exosomal miRNAs	Circulating tumor DNA (ctDNA)	Clinical implications
Biological source	Encapsulated in extracellular vesicles released by tumor cells	Free-floating DNA fragments shed from tumor cells	Determines stability and detection feasibility
Detection techniques	qPCR, microarrays, RNA sequencing (NGS-based approaches)	Digital PCR, next-generation sequencing (NGS), methylation profiling	Advanced technologies needed for clinical adoption
Stability in circulation	High (protected within vesicles, resistant to RNAses)	Moderate (prone to degradation, affected by clearance rate)	Affects reliability for early detection
Tumor specificity	High (derived from tumor microenvironment)	Moderate (includes background ctDNA from non-tumor sources)	Determines accuracy in distinguishing recurrence
Sensitivity for early recurrence	High (detects molecular changes before PSA rise)	Variable (depends on tumor shedding and ctDNA levels)	Affects clinical timing of intervention
Genomic insights	Functional regulatory roles in tumor progression, therapy resistance	Direct detection of tumor mutations, epigenetic alterations	Helps guide targeted therapy strategies
Limitations	Expression variability across patients, lack of standardized protocols	Low ctDNA levels in early recurrence, high cost of sequencing	Standardization and validation required for clinical implementation
Potential for integration	Can complement ctDNA and PSA for enhanced diagnostic accuracy	Valuable for tracking tumor evolution and resistance mechanisms	A multi-biomarker approach may improve surveillance

qPCR = quantitative PCR, PSA = prostate-specific antigen.