An article from the Scientist: "Based on new intelligence, oncologists are making informed battle plans to attack a particularly pernicious enemy - the cancer stem cell (CSC). Controversial though they are, cancer stem cells are an incredibly promising target. If treatment-resistant cancer, and the metastases that transplant the cancer throughout the body, could be attributed to the actions of a single cell type, it could explain many of the treatment failures and provide a novel way to attack the disease. The idea that cancers are driven by cells with 'embryonic features' is an old one. Many cancers regress to a less differentiated state, expressing proteins that are usually expressed only in the embryo or during early development. It is only in the past 20 years or so, however, that additional observations led to the hypothesis that these embryonic-like cells were a separate subpopulation that fueled tumor expansion, much the same way that stem cells churn out the cells that make up a particular organ. ... In the past 5 years there has been an exponential increase in CSC research. This research has helped to resolve a number of controversies regarding identification of these cells and their role in driving tumor growth and mediating treatment resistance. Despite these advances, the CSC field is still in its relative infancy, and many questions and challenges remain. More than a dozen biotechnology and pharmaceutical companies are now vigorously pursuing CSC research. As a result, a number of early-phase clinical trials targeting CSCs are in progress. These studies and the later-stage efficacy trials that follow them should indicate whether successful targeting of CSCs significantly improves outcomes in cancer patients. If this is found to be the case, it may usher in the beginning of a new era of cancer therapy."