Abstract
It is a widely held view that there are self-renewing and multipotent stem cells in most adult tissues and organs and that these cells play a pivotal role in repairing tissue damage. Evidence is rapidly accumulating that a small number of cancer stem cells with similar properties also exist in tumor tissues that mostly consist of non-cancer stem cells, and that the cancer stem cells in turn enable tumor formation. Such cancer stem cells are reported to have characteristic phenotypes, including tumorigenesis, multi-drug resistance, and radioresistance. The cancer stem cell model thus predicts that only the eradication of cancer stem cells, considered responsible for recurrence, will lead to the cure of cancer, implying the importance of a treatment strategy targeting cancer stem cells. Interestingly, the strategies for radiosensitization developed in the radiation oncology field are likely to be closely associated with generating dysfunction in cancer stem cells and niches. Here, we review recent advances in cancer stem cell research, including identification and isolation, and discuss the significance of cancer stem cells as treatment targets.
