kasvajakoes esinevad rakud, mis on võimelised tüviraku kombel iseuuenema ja diferentseeruma ning uusi kasvajaid tekitama, Cancer stem cells (CSCs) are cancer cells (found within tumors or hematological cancers) that possess characteristics associated with normal stem cells, specifically the ability to give rise to all cell types found in a particular cancer sample. CSCs are therefore tumorigenic (tumor-forming), perhaps in contrast to other non-tumorigenic cancer cells. Cancer stem cells were first identified from acute myeloid leukemia in the late 1990s.By now, cancer stem cells have been found from different cancers: breast, colon, brain, ovary, pancreas, prostate, head and skin cancer, melanoma and non-melanoma skin cancer. The number of cancer stem cells in a cancer is typically very low - 1/1000 or even as low as 1/1 000 000.