Recurrent brain tumours are extremely aggressive and despite optimal treatment, median survival is less than two years. One of the standard treatment options in this situation is radiation therapy. Currently there is intense scientific interest concerning the abnormal energy metabolism in cancer cells. All cells require energy in order to function, obtaining 'fuel' molecules such as glucose and fatty acids from the blood stream. Brain tumours exhibit "metabolic reprogramming", meaning that their energy requirements and utilization of fuel molecules are quite different from normal cells. Brain tumour cells are exquisitely dependant on glucose as a source of energy. Animal studies have shown that when these tumours are deprived of glucose they are very sensitive to radiation therapy.