Cancer Stem Cells: The Hidden Driver of Metastasis, Relapse and Drug Resistance (2026)
Medically Reviewed by: Dr Frank Yap, MD | Written by: OneDayMD Editorial Team | Last Updated: August 15, 2026 Key takeaway: Cancer stem cells (CSCs) are not necessarily a tiny, fixed population representing “1% of a tumor.” Their frequency varies dramatically between cancer types and experimental definitions. Modern research increasingly views CSCs as a dynamic cellular state that cancer cells can enter and exit. This plasticity may be as important therapeutically as the CSC population itself. Abstract Cancer stem cells (CSCs) are cancer-cell populations or cellular states characterized by properties such as self-renewal, tumor initiation, differentiation capacity, metabolic adaptation and resistance to therapy. CSC biology has become increasingly important in research on cancer recurrence, metastasis and treatment resistance. However, the traditional model of CSCs as a rare, permanently defined population is being revised. Contemporary evidence supports a more dynamic mo...