Cancer stem cells in relation to treatment.

The classical cancer therapies, including chemotherapy and radiation therapy, can initially show good results and tumor shrinkage; however, for most cancer patients disease recurrence is a common event. This tumor regrowth following therapy is now thought to depend on a small population of cancer stem cells (CSCs), which, similar to other stem cells, have the capacity for self-renewal and multipotent differentiation. Cancer stem cells have been identified based on cell surface protein expression in many tumor types, and for all diseases studied, this specific cell population is required for serial transplantation in animal models. However, a specific signature of cell surface proteins that can identify cancer stem cells has not been developed for many solid tumors. In this review, we summarize a new technique for identifying and quantifying cancer stem cells in situ, which could be a valuable technique for evaluating the effects of therapies on this cell population. Finally, we conclude by discussing several preclinical treatment strategies that either reprogram cancer stem cells or cause them to be specifically attacked by immune cells. In summary, therapeutic and diagnostic methodologies that can attack and quantify cancer stem cells, respectively, will be valuable tools for eradicating cancer.