Until recently, the universally accepted dogma in cancer research stated that replicating cells accumulate several rounds of mutations before becoming cancerous. According to that dogma, the mutations that result in metastatic spread throughout the body occur late in tumor progression. This idea has recently been challenged by the identification of cancer stem cells (CSCs), which provide a new explanation for both the initiation and propagation of tumorigenesis. Rather than following a linear process that starts with unchecked replication and ends with the loss of adhesion molecules that drives metastasis, CSCs can self-renew, proliferate, differentiate, and even revert back to a stem cell state, producing metastatic cells at unexpected stages of the disease.
With a new understanding that cancer progression does not necessarily follow a particular order, researchers have been looking for models to help explain how and when cancers become aggressive. While the idea of CSCs helps explain some observations ...
