The article discusses the concept of pre-metastatic niches (PMNs), which are organ-specific microenvironments that support the survival and growth of cancer cells before they reach distant organs. These niches are formed by factors secreted by the primary tumor and extracellular vesicles, which alter the local environment to facilitate metastasis. The formation of PMNs involves vascular leakiness, recruitment of bone marrow-derived cells, and the creation of a supportive microenvironment for circulating tumor cells (CTCs). The article highlights the role of various factors, including tumor-secreted factors, exosomes, and inflammatory molecules, in the development of PMNs. It also discusses the importance of PMNs in organ-specific metastasis and the challenges in studying them clinically. The review emphasizes the complex molecular and cellular processes involved in PMN formation and their implications for cancer progression and treatment. Key findings include the role of S100 proteins, the influence of tumor-derived exosomes, and the importance of the immune system in PMN development. The article also addresses the challenges in understanding PMNs, such as the difficulty in tracking them in real time and the need for better imaging techniques. Overall, the study underscores the significance of PMNs in metastatic cancer and the need for further research to develop targeted therapies.The article discusses the concept of pre-metastatic niches (PMNs), which are organ-specific microenvironments that support the survival and growth of cancer cells before they reach distant organs. These niches are formed by factors secreted by the primary tumor and extracellular vesicles, which alter the local environment to facilitate metastasis. The formation of PMNs involves vascular leakiness, recruitment of bone marrow-derived cells, and the creation of a supportive microenvironment for circulating tumor cells (CTCs). The article highlights the role of various factors, including tumor-secreted factors, exosomes, and inflammatory molecules, in the development of PMNs. It also discusses the importance of PMNs in organ-specific metastasis and the challenges in studying them clinically. The review emphasizes the complex molecular and cellular processes involved in PMN formation and their implications for cancer progression and treatment. Key findings include the role of S100 proteins, the influence of tumor-derived exosomes, and the importance of the immune system in PMN development. The article also addresses the challenges in understanding PMNs, such as the difficulty in tracking them in real time and the need for better imaging techniques. Overall, the study underscores the significance of PMNs in metastatic cancer and the need for further research to develop targeted therapies.