Orchestrating Tumor Metastasis: Exosomes as Master Regulators of the Local and Distant Microenvironment

Metastasis remains a critical challenge in oncology and constitutes the leading cause of cancer mortality. Recent studies have revealed that exosomes are involved in every step of the cascades of tumor invasion and metastasis. Therefore, it is necessary to further investigate the exosome-mediated intercellular communication network within the tumor microenvironment to elucidate the mechanisms of cancer metastasis. This review summarizes alterations in the tumor microenvironment at primary and metastatic sites during metastasis, encompassing processes such as epithelial-mesenchymal transition (EMT) induction, extracellular matrix (ECM) remodeling, immune suppression, and angiogenesis. In addition, we examine the role of exosomes in mediating tumor drug resistance and explore the clinical translational potential of exosomes in biomarker detection, drug delivery systems, and cancer vaccines.