Heterogeneity of CTC Contributes to the Organotropism of Breast Cancer

Circulating tumor cells (CTCs) are viewed as pro-metastasis precursors shed from primary tumors or metastatic sites. The phenotypic and molecular heterogeneity of CTCs is associated with breast cancer progression and prognosis. Therefore, we divided CTCs into several subtypes according to their differences in biomarker status, epithelial/mesenchymal phenotype, aggregation status, and other factors to summarize their characteristics. Considering that the organ-specific metastasis is a hallmark of breast cancer, we adopted the "seed and soil" model to further analyze the relationship between the heterogeneity of CTCs and the organotropism of breast cancer. We speculated that CTCs might not only develop their genetic potential but communicate with surroundings, including chemokine systems, hemocytes, and extracellular matrix components, to regulate the organ-specific metastases of breast cancer.