Cancer Metastasis and Cancer Stem Cells

Increasing amounts of evidence have indicated the important role of cancer stem cells (CSCs) in tumorigenesis and relapse. Metastasis is a key biological characteristic of malignant tumors. How cancer cells spread from the original tumor into the circulation and then infiltrate distant organs remains a topic of debate. Moreover, understanding the differences between metastasized and non-metastasized cancer cells is the key to develop strategies to block metastasis. In this review, we summarized the development of the CSC theory related to tumor metastasis over the last two decades.