Kinga Suska, Marcin Piotrowski, Damian Jacenik, Jakub Fichna
Colorectal cancer (CRC) remains one of the leading causes of cancer-related mortality worldwide and is frequently diagnosed at an advanced stage due to limitations of current screening methods. Although surgical resection is the standard treatment, conventional tissue biopsies are invasive and restrict real-time assessment of tumor dynamics. Liquid biopsy has emerged as a promising noninvasive approach enabling repeated analysis of tumor-derived components in body fluids. Among these, exosomes have gained considerable attention as potential diagnostic biomarkers in CRC. This review summarizes current evidence on exosome biogenesis, molecular composition, and their diagnostic relevance in colorectal cancer. We discuss exosomal nucleic acids, proteins, and lipids as biomarkers detectable in patient samples, as well as analytical platforms used for their isolation and characterization, including ultracentrifugation-based methods, size-exclusion chromatography, nanoparticle tracking analysis, electron microscopy, proteomics, lipidomics, and sequencing approaches. Accumulating data demonstrate that exosomal microRNAs, long non-coding RNAs, proteins, and lipid signatures correlate with tumor progression, immune modulation, angiogenesis, and epithelial-mesenchymal transition. Advances in microfluidic technologies, Raman/SERS spectroscopy, and AI-based data analysis are contributing to further improvements in diagnostic sensitivity and reproducibility. Despite their potential, the lack of standard isolation and validation protocols remains a major obstacle to clinical implementation, highlighting the need for large-scale multicenter studies before exosome biomarkers can be routinely used in CRC diagnostics.