Canadian scientists have demonstrated that many cancers depend on "cancer stem cells" to grow and spread.
Dr. [John] Dick's discovery of the first cancer stem cell that year has led to the flurry of recent breakthroughs redefining cancer biology. Scientists once believed all cancer cells could sprout and sustain a tumour. But proof is growing that this deadly power belongs only to a tiny subset of abnormal stem cells that had previously gone undetected. These bad seeds have now been identified as the source of cancers of the blood, breast, bone, prostate, and this week, in another finding from Dr. Dick, the colon.
The implications are staggering. Billions of dollars and decades of research may have targeted the wrong cells to cure the disease. No current treatment has been designed to kill them and they appear to be naturally resistant to the gold-standard therapies.
It's an amazing advance that's easily summarized:
1. Tumors (and blood cancers) appear to depend on cancer stem cells for growth. Fewer than 1% of tumor cells are stem cells, and non-stem cells won't grow a tumor on their own.
2. Cancer stem cells appear highly resitant to chemotherapy and radiation, which mainly kill the other 99% of a tumor's cells and cause the tumor to shrink.
When new treatments are devised that can target the cancer stem cells, it may be possible to completely eradicate most cancers.