The cancer stem cell theory states that tumor growth is driven by a small number of dedicated cancer stem cells (CSCs). These cells are endowed with the ability to self-renew (leading to unlimited cell division and maintenance of the stem cell pool), differentiate into non-CSCs and are intrinsically resistant to conventional therapeutics. This theory explains the clinical observations of almost inevitable tumor relapse after initially successful chemo and/or radiotherapy, and metastasis. This module reviews the biology of CSCs and provides insights into CSC plasticity, interaction with the niche, tumor repopulation and clinical implications of therapeutic response.     

Learning Objectives

• Explain the difference between the clonal evolution model and the CSC model
• Define a stem cell
• List the key characteristics of a CSCs 
• Define cellular plasticity and explain why it is important within the tumor
• Describe the epithelial-to-mesenchymal transition 
• Explain the Warburg effect