48 ABSTRACT CANCER STEM CELL POPULATION AND METFIOD FOR PRODUCTION THEREOF5 An objective of the present invention is to provide a population of cancer stem cellsfrom which cells with no cancer-forming ability have been substantially removed, wherein the population has a feature of reproducing the cancer-tissue hierarchical structure； and methods for producing and using the same. To achieve the above objective, the present inventors repeatedlygrew human cancer tissues in NOG mice, and then isolated cancer cells for comparing various10 culture methods. As a result, the present invention is completed by successfiilly obtaining ahomogeneous cancer stem cell composition in which cells having cancer-forming ability does not substantially coexist and cells without cancer-forming ability by an adherent culture method using a serum-free stem cell medium, rather than by a routine floating culture method.15 I No Suitable Figure
