**Abstract**

Extracellular vesicles (EVs) are biological active vesicles and carriers of information in intercellular communication. In cancer settings, EVs especially exosomes (Exo), play a focal role in modulating the tumor microenvironment mainly by increasing tumor proliferation, facilitating the crosstalk between tumor and tumor-neighboring cells, and influencing the host immune response. Amongst these functions in tumor growth, Exo modulate fundamental steps of tumor progression, such as growth, invasion, and immune modulation. On the endocrine level, Exo released from tumors were shown to mediate distant cell-cell communication processes via secretory factors and miRNAs, which result in the set-up of pro-tumorigenic microenvironments supportive of metastatic dissemination. This is achieved through processes such as fibroblast activation, extracellular matrix ECM production, angiogenesis, and immune modulation.

**Keywords:** tumor microenvironment, exosomes, tumor progression, metastasis, targeted therapy
