According to a paper in yesterday’s Journal of Clinical Oncology, the 5 year survival rate of children with acute lymphoblastic leukemia (the most common form) has continued its upward trajectory, and now stands at 90 percent–fairly amazing considering that it was almost always fatal as recently as the 1960s.
This should not be taken as evidence that the end of cancer is around the corner–it is not. Although there have been a few cancers that are either curable (testicular, for example), preventable (cervical) and more treatable (breast), progress against the disease has, for the most part, been incremental and slow. A recent paper in the New England Journal of Medicine offers an peak into why this may be.
When Dr. Marco Gerlinger of the Cancer Research UK London Research Institute and his group examined the genetic makeup of kidney tumors and compared it to that of metastases from the same tumor, they found unexpectedly large differences between the genetic makeup of the original tumor and the cancer that had metastasized. Oncology researchers have long known about mutation of cancer cells, but until this week they didn’t appreciate the magnitude of the process. According to Dr. Merlinger, in real life “…a serious flaw in the imagined future of oncology is its underestimation of tumor heterogeneity.”
The authors logically concluded that a single needle biopsy of a cancer mass will tell you little or nothing about the genetics of any other masses within the body, and that this would make personalized treatments very difficult. But the implications of this are worse.