A team led by Irving Weissman at Stanford University School of Medicine has found the cancer-initiating stem cells in melanoma. According to a Stanford press release:
The finding is significant because the existence of such a cell in the aggressive skin cancer has been a source of debate. It may also explain why current immunotherapies are largely unsuccessful in preventing disease recurrence in human patients.
That's because any therapy that kills the bulk of the tumor without eliminating the cancer stem cells won't be effective:
Any therapy that doesn't wipe out these elite cancer stem, or initiating, cells has no chance of completely eradicating the disease even if it destroys nearly all other tumor cells. That's why, say proponents, it can be relatively easy to get a patient into remission, but extremely difficult to prevent the cancer stem cells from roaring back and causing a relapse months or years later.
The work was published in the July 1, 2010 issue of Nature.