Cancer stem cells and tumor radioresistance

Cancer stem cells (CSCs) in a variety of tumor types have intrinsically greater resistance to ionizing radiation (IR) than the remaining cancer cells. Since surviving CSCs have the capacity to regenerate tumor deposits, CSC radioresistance represents an important clinical problem. Here we discuss mechanisms that CSCs employ to resist IR and therapeutic strategies that are currently being used in the clinic or are in various stages of development for overcoming these. While much ongoing work shows promise for increasing the efficacy of IR through rational targeting of CSCs, well-designed clinical trials testing such strategies will be required to bring these approaches into the clinic.