Cells shed from solid malignant tumors into the circulation are considered to be the origin of metastases. In spite of a wealth of research on the pathway of metastasis formation, it is still not clear when and how metastases develop, nor is there a consensus on the number and the nature of circulating tumor cells present in individual patients and their relationship to the formation of metastases. We have developed a method to detect a maximum of unselected non-hematological, epithelial cells in the blood, assuming that in cancer patients the majority of these cells are derived from the tumor. Assessment of the number of these cells longitudinally during the course of disease and therapy allows the response to different treatments to be monitored. Due to the viability of the cells, additional analyses such as expression profiles and determination of their sensitivity to drugs can be performed.
Keywords: breast cancer; chemosensitivity testing; chemotherapy monitoring; circulating epithelial tumor cells; maintenance therapy monitoring; tumor spheres; tumor stem cells.