For over 50 years, the field of cancer therapy has been dominated by the concept that the tumor must be the selected target of the chemotherapy delivered. Therefore, any drug with the ability to directly kill tumor cells in the laboratory was by definition a candidate for use as chemotherapy in humans. However, because of the high mutation rate of cancer cells (genetic instability), repeated exposures to chemotherapy often results in a population of residual tumor cells that have become resistant to the effects of the chemotherapy. It is this genetic instability and the development of resistance to therapy that has most hindered our success in finding a cure for childhood brain tumors.

by Roger J. Packer, M.D.

Significant progress has been made in the management of some forms of childhood brain tumors. However, for children with malignant gliomas including those of the cerebral cortex, diencephalon, brain stem, or cerebellum, progress has been frustratingly slow. The majority of these children, despite treatment with aggressive surgery, radiation therapy, and chemotherapy, will die of progressive disease within three years of diagnosis. The outcome is even poorer for children with recurrent malignant gliomas, as few of these children will survive for greater than nine months from the time of tumor recurrence.