Exosomal biomarkers: A novel frontier in the diagnosis of gastrointestinal cancers

Table 6 Limitations for the use of exosomal biomarkers

Limitation aspect	Details
Extraction and isolation	Techniques are not widespread and have limitations. Different isolation methods produce distinct EV subpopulations with variations in miRNAs, proteins, diameters, and functions. Purity of exosomes is a major concern as it impacts diagnostic accuracy
Standardization	Lack of standardized operating procedures and data - handling methods. Current liquid biopsy clinical guidelines lack uniform and robust evidence. Variations in sensitivity and specificity occur due to different detection techniques/assays
Large scale clinical validation	Sample sizes in relevant studies are insufficient, data are limited, and validation periods are often too short to draw definitive conclusions. Most studies focus only on specificity and sensitivity of exosome detection systems, neglecting other crucial aspects like consistency, reproducibility, accuracy, reference ranges, and minimum detection limits

EV: Extracellular vesicle; miRNA: MicroRNA.