Cancer stem cells
There is now abundant evidence that stem-cell properties are highly relevant to the biology of several human cancers. However, many key questions remain. At the most fundamental level, we must determine to what extent stem-cell biology is relevant to all the major forms of human cancer. For this reason, it is premature to overstate the general role of stem cells in cancer. Nonetheless, the eradication of cancer stem cells will be necessary to improve the outcome of treatment for at least some cancers. An interesting question is whether different types of cancer stem cells have the same Achilles' heel; it should be possible to determine whether the same tumor-specific mechanisms of growth and survival are active across multiple cancer types. Because certain features of normal stem cells are conserved in different tissues,81 determining whether there is similar conservation among cancer stem cells will be useful in the design of new therapies. Another important issue to investigate is how existing chemotherapy agents affect the evolution of cancer stem cells during conventional treatment regimens. This question relates to both the sensitivity of normal stem cells, as compared with malignant ones, and the mechanisms by which drug resistance may arise. Do current forms of treatment provide a competitive advantage for cancer stem cells, and if so, does that selective pressure drive the emergence of drug resistance in cancer stem cells? Finally, it will be critical to evaluate the clinical end points by which treatment success should be measured. The eradication of bulk disease is not likely to predict the efficacy of drug regimens for rare cancer cells. Therefore, the development of assays that measure the survival of cancer stem cells will be important for assessing the potential of new targeted regimens. Copyright © 2006 Massachusetts Medical Society.
Digital Object Identifier (DOI)
Additional Document Info
has global citation frequency