[Tumor stem cells--a possible scenario].

More and more evidence support that tumors arise from somatic stem cells or from cells, either progenitors or differentiated ones, with the properties of stemness. It is a question whether all tumor cells have the capacity for self renewal and unlimited growth or only a fraction of them, i.e. the tumor stem cells. The concept is challenging, since the existence of tumor stem cells has an important practical consequence: only stem cells should be removed or stopped in order to control the tumor, while the other cells have temporary proliferative capacity.