The state of cancer research is a frequent topic on this blog (for example, here, here and here), so this NY Times excerpt from Columbia oncologist Siddhartha Mukherjee’s new book – Emperor of All Maladies: A Biography of Cancer (Scribner November 16, 2010) – caught my eye. It’s well worth a read:

Why does cancer relapse?  .  .   . when a cancer disappears on a CT scan or becomes otherwise undetectable, we genuinely begin to believe that the disappearance is real, or even permanent, even though statistical reasoning might suggest the opposite. A resurrection implies a previous burial. Cancer’s “relapse” thus implies a belief that the disease was once truly dead.

But what if my patient’s cancer had never actually died, despite its invisibility on all scans and tests? .  .  .

In fact, this view of cancer – as tenaciously persistent and able to regenerate after apparently disappearing – has come to occupy the very center of cancer biology. Intriguingly, for some cancers, this regenerative power appears to be driven by a specific cell type lurking within the cancer that is capable of dormancy, growth and infinite regeneration – a cancer “stem cell.” [.  .  .]

But if tumors contain dedicated stem cells, then delivering maximal doses of poisons to kill the bulk of the tumor might achieve one response – a shrinkage of the tumor – but have no effect on relapse. If the rare stem cell lurking within a tumor somehow escapes death, then it will reassert itself and grow again. Cancers will come back like a garden that has been cleared by hacking at its weeds while leaving the roots behind. [.  .  .]

If such a phoenix-like cell truly exists within cancer, the implication for cancer therapy will be enormous: this cell might be the ultimate determinant of relapse. For decades, scientists have wondered if the efforts to treat certain cancers have stalled because we haven’t yet found the right kind of drug. But the notion that cancers contain stem cells might radically redirect our efforts to develop anticancer drugs. Is it possible that the quest to treat cancer has also stalled because we haven’t even found the right kind of cell?