CANCER STEM CELLS: Redefining the Paradigm of Cancer Treatment Strategies

Carcinomas arising from activated cancer stem cells in different types of tissue. Embryonic tumors arise from normal embryonic stem cells. They are already rapidly dividing (activated) and require few alterations to become malignant. Conditional growth tissues such as the breast are activated by hormones during puberty and during reproductive life. Activated stem cells in these tissues suffering tumor suppressor gene mutations give rise to premalignant lesions progressing to malignancy. Renewal tissues such as the colon and skin have dormant or slowly replicating stem cells. Certain tumor suppressor gene mutations give rise to activated stem cells with uncontrolled replication. Subsequent mutations give rise to tumor progression.