# Exosome crown proteins are promising markers for liquid biopsy of breast cancer

## TL;DR

Exosome surface proteins show promise as reliable and early diagnostic markers for breast cancer through liquid biopsy.

## Contribution

This review specifically evaluates surface-accessible exosome proteins for their diagnostic potential, bridging EV biology with clinical assay design.

## Key findings

- Exosomal crown proteins offer tissue-specific and analytically feasible advantages over other tumor markers.
- Flow cytometry enables simple and reproducible analysis of these proteins for diagnostics.
- Standardization of protocols is essential for clinical implementation of exosome-based diagnostics.

## Abstract

Breast cancer (BC) remains the most common malignant disease in women. However, currently used instrumental and laboratory (CA15-3, CA125, etc.) diagnostic methods demonstrate insufficient sensitivity and specificity for early and reliable detection of BC. In this regard, great expectations are associated with the liquid biopsy method based on the identification of tumor cells or their components, including tumor-derived exosomes. The purpose of this study is to analyze current data on exosome proteins that can be used for diagnostics using liquid biopsy. This review discusses the role of exosomal crown proteins in the spread of BC and assesses their potential as diagnostic markers. The undoubted advantages of using exosomal crown proteins as tumor markers compared to other components of the tumor secretome are the simplicity and reproducibility of their analysis by flow cytometry, as well as, unlike microRNA, tissue specificity. In contrast to prior reviews that primarily catalogue extracellular vesicle cargo, we specifically assess surface-accessible proteins that combine biological relevance with analytical feasibility. This approach bridges mechanistic EV biology with the practical design of clinically translatable diagnostic assays. Standardization of protocols for exosome isolation, antibody validation, and signal amplification will be critical to the successful implementation of this approach into routine clinical practice. Integration of exosomal coronary protein profiling into modern oncology workflows may open new opportunities for early detection, long-term surveillance, and precision treatment of BC.